I have an earlier answer that addresses part of your question!

• Is it true that women couldn't buy property in the US prior to 1974?

Goodness gracious no. And the Equal Credit Opportunity Act referenced in that post, while it does indeed prevent discrimination on the basis of marital status, is about the extension of credit (loans), not possession of property.

That said, the inclusion of marital status in the act (Title VII of the Consumer Credit Protection Act) was part of the final death of coverture in the US.

America was a British colony and thus derives its law code in large part from English common law, including the doctrine of coverture. Under coverture, married women were not actually legal persons--they were essentially treated like legal minors under their husbands' authority. All property was joint property (including any wages earned) and husbands had final say; women could not sue in court, make contracts, or buy and hold their own property.

Note that in America as in England, this applied to married women, or feme couvert ("covered" women). Widows and single adult women were classified as feme sole, full legal persons who could independently buy, own, and sell property, make contracts, and represent themselves in court.

The practical realities, enforcement, and effects of coverture are a contentious question in scholarship whether you're talking about the fifteenth century or the nineteenth. However, from the mid-ish 19th century to the 1970s we see a gradual ebbing away at coverture on a legislative level--on a state by state basis. (You'll notice that these two periods correspond to periods of flourishing women's rights activity. Not a coincidence.)

In the 1970s, some degree of coverture laws continued to apply in U.S. states like Louisiana, although very few of them. A series of Supreme Court decisions extended equal protection laws to marital status, which feminist legal scholars have considered to mark the final death of coverture. (I think this is why the AskReddit user's source picked out the 1974 law as significant, although not the significance that the post claims). Louisiana's "head and master" law, which legally placed the husband in control of the marriage and marital assets, was finally abolished by the Supreme Court in 1981 in Kirchberg v. Feenstra.

I can answer part of this question, mainly the legislative background and history of the ECOA and partly how RBG is related to it. Please note that US social history is only tangentially related to my field, so i could be missing something on the ACLU or RBGs relation to the ECOA.

---

Tl;dr: Women could both get mortgage and have a bank account. Rather, their practical opportunity to do so was limited by discriminatory cultural views and the practices of banks and creditors, this especially hit married women, as the husband was seen (also by some laws) as the head of the household finances and responsible also for the rights of the wife.

RBG didn't solve this herself, it's not solved by a court case (though, it did follow in the footsteps of court cases), but by legislative action that RBG, along with many others, were advocates for, this being the ECOA.

---

The Equal Credit Opportunity Act and it's background

Credit discrimination was made illegal with the Equal Credit Opportunity Act (ECOA) of 1974 15. U.S.C. 1691, amending title VII of the 1968 Consumer Credit Protection Act. ECOA made it illegal to:

discriminate against any applicant, with respect to any aspect of a credit transaction, on the basis of (…) sex or marital status (…)”.

The Federal reserve board, on the basis of this, gave further implementing regulations (Regulation B) stating that:

“[A] creditor shall not require the signature of an applicant's spouse or other person, other than a joint applicant, on any credit instrument if the applicant qualifies under the creditor's standards of creditworthiness for the amount and terms of the credit requested

On the purpose of the ECOA, a disctrict court case (CMF Virginia land, L.P v. Brinson) states that the purpose is to eradicate credit discrimination against women, especially married women, who creditors typically refused to consider individually. Furthermore that:

It is well-documented that, prior to the ECOA, it was customary for lenders to require the guarantee signatures of husbands whose wives sought credit, even when a credit check would have revealed that the wife was creditworthy on her own

So there is a reason why ECOA mentions both sex and marital status, there were special cases of sex discrimination that hit married women extra hard, because the intertwined attitudes towards both women in general, and the cultural views on marriage, both became a limiting factor. Both also having a long historical expression in law^(1).

In the deliberations up to the ECOA, we have a report (1972) from the National Commission on Consumer Finance, which had studied the availability of credit to women, and they describe five key issues, which Margaret Gates (1974) cites as following:

• Single women have more trouble obtaining credit than single men. (This appeared to be more characteristic of mortgage credit than of consumer credit.)
• Creditors generally require a woman upon marriage to reapply for credit, usually in her husband's name. Similar reapplication is not asked of men when they marry.
• Creditors are often unwilling to extend credit to a married woman in her own name.
• Creditors are often unwilling to count the wife's income when a married couple applies for credit.
• Women who are divorced or widowed have trouble re-establishing credit. Women who are separated have a particularly difficult time, since the accounts may still be in the husband's name.

Gates also describes further problems not mentioned, including:

• Refusing to issue her an account for which she would be eligible were she not married,
• requesting information concerning her husband's creditworthiness before doing so,
• considering her a "dependent" of her husband when calculating his eligibility for credit,
• applying stricter standards when the wife rather than the husband is the primary wage-earner, and
• altering her credit rating on the basis of her husband's credit performance.

So credit could be a problem both for single and married women. Single women in a sense had more freedom, as the restrictions on married women were often tied specifically to the concepts of marriage, but single women faced other issues that made it harder for them to get credit than men.

Part of what would have been a problem for single women was the fact that they were assumed to soon be married and then leaving the workforce, which would factor into their independent credit ratings. There was also just blatantly sexist reasons for denying loan applications that hurt all women, like the idea that they were worse with money or could not do property maintenance like men, thus the property would fall more in value. Furthermore women were often hurt by a lack of credit history.

All this was done to the contrary of evidence at the time, which indicated women were equal or better creditors. There were some laws that the credit companies claimed made it difficult to treat women the same, this was not really the case, but the laws do illustrate that the law often treated men and women differently as well, such laws were especially the case for married women^(2).

So overall women had the same formal right to take up credit and buy a house, but there were practical, cultural and legal barriers in the way of doing so, as discrimination was allowed. Solving some of the practical and cultural barriers for women to get credit was the goal of ECOA.

^(1. An example is the old case) ^(Brandwell v. The State 1872) ^(stating that the paramount destiny and mission of women is to become a wife and mother.)

^(2. Examples being,) ^(support laws) ^(where husbands had to support women. Women could thus buy on the Husbands credit, at least to a degree, a concrete example are Family expense laws, which makes it possible for creditors to seek expenses from both the husband and wife for family expenses regardless of who signed it.)

^(Further laws were some state’s) ^(property laws, which automatically made the husband the manager of the property, though by this time those states had mostly changed them to allow women some independence in managing her earnings, with Louisiana being the holdout. There were also laws limiting the ability to have separate accounts,) ^(multiple agreement laws) ^(meant to limit creditors abuse of charging in practice higher interests by having them in several separate loan agreements.)

^(Divorce and separation laws) ^(also caused issues)^(,) ^(the issue not being the law itself, but rather how marriage and divorce typically meant the man has done all the borrowing, and the divorced woman would be a “new face” as a creditor, and culturally seen as risky or unstable.)

Continued below

For background: there is a long history in English and American law of women losing rights upon marriage. Coverture, as I've explained in past answers like this one, meant that a woman who married was sucked into her husband's legal identity. Therefore a number of things that required a legal agreement required her husband's signature/consent alongside hers, and a married woman had no control of her earnings or property if her husband chose to dispose of them. Women who had inherited property or money before they married would lose it to their husbands as well.

Coverture as a legal principle began to be dismantled over the nineteenth century in both the United Stated and the United Kingdom. In the United States, the repeal of coverture and the advance of women's rights had only happened on a state-by-state basis, which meant that there were different standards everywhere, but by the end of the century, all(?) states had laws on the books ensuring that married women were at least entitled to their own earnings and property.

But we aren't just talking about coverture, we're talking about women's equality to men, period. So, the fourteenth amendment of the US constitution states:

No state shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States; nor shall any state deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws.

If this principle were always followed, we would live in a utopia. In the mid-twentieth century, states had routinely made and enforced laws that abridged the rights of women and people of color, and failed to give them the equal protection of the law. The 1961 Supreme Court case of Hoyt v. Florida even explicitly upheld the lack of protection to women: Gwendolyn Hoyt had killed her physically and emotionally abusive husband in self-defense, and was convicted almost immediately by an all-male jury, as the state required all men to serve on juries and only allowed women to do so on request; SCOTUS ruled that women should be protected from the "filth" of the courtroom and that all-male juries were normal in the United States. As a young lawyer at the time, Ruth Bader Ginsburg began taking cases to challenge that lack of protection. And although she would eventually do great work against discrimination as a judge, typically people who are talking about what she accomplished for women's rights in her career are referring in large part to her work as a lawyer.

The landmark case that brought the Equal Protection Clause to bear on women's rights is Reed v. Reed (1971). Sally and Cecil Reed were divorced, and Sally had been unable to keep full custody of their son as she had wanted. While at his father's house, their son apparently committed suicide with one of Cecil's guns. Both parents filed to be the administrator of his estate (Sally actually submitting her petition first), but it was in Idaho state law that men must be preferred to women when it came to estate probate, so Cecil was given their son's belongings. This traveled up the chain to the United States Supreme Court, and Ginsburg wrote the brief defending Sally Reed's rights along with the director of the ACLU. SCOTUS found in her favor, and it was deemed unconstitutional to enshrine a preference for one gender over another in law; Congress would go on to rewrite a number of laws that had done so.

While it wasn't the full closed-door to sexism that Ginsburg and others had hoped, it provided a great precedent for later cases - often involving Ginsburg! - to say, "no, you can't legally discriminate based on gender" in other specific ways, which is something that had not previously been done before. The following year, Ginsburg would set up and lead the Women's Rights Project in the ACLU in order to put and keep equal rights for women on the organization's radar, which does mean that she deserves credit for the good work the WRP would go on to do in fighting for equal rights for women. She was involved with other SCOTUS cases dealing with gender bias enshrined in law throughout the 1970s, including Moritz v. Commissioner (1972), which struck down a law that allowed a state allowance for hiring a home health aide only if you were a woman or widowed man, and Frontiero v. Richardson (1973), which required the military to give benefits to male dependents of female officers just as it did female dependents of male ones.

Your question is challenging for one single person to answer as it crosses over multiple domains. Which, to be sure, is a good thing. It speaks to how complicated history – and doing history – can be. I’ll defer to those with more familiarity with the law to speak to these specifics, but I can speak to your clarifying questions, “What were the legal justifications behind denying women these basic rights?” as it crosses over into my field of education.

First, though, we have to be clear about which women we’re talking about when we’re talking about women and the law in America. In 1989, Black feminist scholar Kimberlé Williams Crenshaw created the legal framework she called “intersectionality” to identify how the law impacted women differently based on their race and other aspects of their identity. The clearest example of this is the 19th Amendment. Although the Amendment prohibited states from preventing people from voting on account of their gender, they could still use race as a factor. (Our recent AMA with Dr. Martha Jones is a great read on the topic. As is her new book!) In effect, the path that non-disabled cis white women followed and/or forged is different than the path followed by Black, Indigenous, Hispanic, Pacific Islander and Hawaiian, and Asian women in America. So, generally speaking, we’re talking about white women when we’re talking about women’s rights and the laws.

When we consider your question, it’s helpful to reframe it less as rights denied and more as rights seen as superfluous. In effect, a woman didn’t need to do the things you described. After all, a woman would go from her father’s house to her husband’s house. Her responsibilities included the domestic sphere (more on that in a bit) and legal matters were outside that sphere. Because people are complicated, there were a variety of complicated rationales for this worldview and a few simplistic, sexist ones. There were, of course, men (and women) who felt that women are less than men; less intelligent, less capable. Others felt that caring for the girls and women in his life was a man’s responsibility. As such, if a woman needed to do things related to the law, a man around her was failing to fulfill his obligations. And others felt such things were too trivial for a woman to have to deal with as she needed to focus her energy on her children. Etc. etc. Of course, there were women (and men) who disagreed with these rationales. Quaker communities typically raised their children with an eye towards equality. Widows have existed as long as marriages as existed. Women needed to and could handle the legal matters they might encounter, so although there were prevailing sentiments, there were women who ignored them and did what they need to do. Women have always owned businesses and provided services outside the home in America. The sentiment was less about what did happen and more what white, Protestant culture said should happen.

Regardless of the rationale for why, the idea why women didn’t need to the things listed in the post generally comes down to the idea that each gender was responsible for different aspects in the home. Women, seen as the gentler gender, was responsible for the maternal aspects of the home including care taking, aesthetics, child raising, and such things. In the eyes of many, there was a sense of equality behind this division. Rather than being seen as less than by many, women’s work was seen as equal to but different than men’s work outside the home. Which leads us to education.

Even in the earliest forms of formal education, there was a division along gender lines regarding what was seen as "appropriate" for girls and women. “Dame schools”, an early version of daycare and primary school common in colonial America, were primarily run by women in their homes, typically while running an in-home business of their own. Although they would educate boys and girls alike, the women usually limited instruction to basic literacy and social norms with the expectation the boys would learn the math they needed from their male teachers or tutors when they got to academy or school. This division of content for the student and labor for the adults is referred to as "soft segregation." (In contrast to “hard segregation” based on race. They’re separate but related concepts; it wasn’t really until after Brown v. Board in 1954 that a white female student having a Black male teacher became something that could happen.)

These two concepts: soft segregation and the domestic sphere, shaped a great deal of early American education, with connections to legal and policy matters. Beginning with the earliest laws in Massachusetts related to education, Protestant leaders advocated for mixed-gender literacy as Satan was as likely to pull a girl from the path to a righteous future as a boy if she was unable to read the Bible. This meant that women would teach girls and boys to read as raising a sufficiently spiritual child was part of a mother’s responsibility. However, the moment the education moved from the spiritual to the corporal world, the soft segregation kicked in; girls shifted to learning the domestic arts, boys to learning all the other stuff. Likewise, with laws. Contracts, money matters, etc. were outside the spiritual domain or the domestic sphere. Women didn't need to worry about that stuff. As it were. However. Women would be encouraged to learn domestic math - in case their husbands needed assistance. One early advocate of tax-payer funded education, Benjamin Rush, was very insistent on girls learning bookkeeping to assist their future husband and often wrote about girls' "peculiar" education. Again, the difference between what was/is and should be; her education wasn't though in service to her (even if she did end up using it to help herself), it was in service to her role as a future helpmate and mother.

Early in the rise of the common school movement, advocates worked to persuade fathers that becoming a teacher fit inside this notion of the domestic sphere. That, by teaching, a young woman was preparing for her life as a wife and mother. (I wrote more about this in this piece on the link between gender roles and school decorations.) To say they were successful is putting it mildly. By the 1870s or so, nearly half of white women living in Massachusetts had worked as a teacher at some point in her life. However, as soon as a young woman got engaged or married, she typically left the classroom as her responsibilities were now to her husband and children. Because, again, she didn't need to work if she had a husband. Later, through sheer force of will (often led by women teachers who were caring for younger siblings or raising a child on their own), women teachers persuaded the men in positions of leadership that a woman could teach and be a wife or mother. It wouldn’t be until the 1980s that women could legally teach, be married, have children, and be pregnant. All at the same time. (Much like a variety of sentiments related to why women didn’t need access to the same legal and financial services as men, people had a lot of opinions about the impact of pregnant teachers on children.)

This history matters as it helps us understand the mindest that went into those laws and some of the tactics used by feminists, lawyers, and activists like Ginsburg to change them. One of her approaches was to highlight how sex-based laws hurt men as well as women. Other activists, like those in education, worked to expand the definition of the "domestic sphere" in order to expand the places and ideas where it was "acceptable" for women to be. So while it's accurate to say the laws are based in the systematic sexism (and racism and ableism) that shape America, it's also fair to say that the men who authored the laws didn't exclude women, in many cases, it simply didn't occur to them to include them.

When my mother needed a major appliance ( I think it was a new washer) my dad had to go to Sears with her to ok her buying it, even tbough he was a student and she was the wage earner. A generation later I'm able to buy a house and cars on my own. One generation, thanks to women like RBG. I think women of my generation (born in the 50s or 60s) appreciate the change. I hope the younger women don't take it fir granted.