I've never posted here, but I'm hoping this question might work better here then say, something like askreddit (where frankly, I've never once got a answer to any question).
Obviously, I'm pulling largely from movies or fictional novels, so I assume that the story perhaps might gloss over inherently greater health issues. What bothers me, though is that it often appears that in stories that reflect upon, let's say everything prior to the early 1900's you'll find people just up and dying from a flu or the common cold. Half the time in a book like Wuthering Heights or something, a character gets a fever and it's considered that the end is in sight.
People often will say, oh, we have better medicine or hygiene, but as I currently have a very bad cold, one thing is clear: without any medical attention I will surely not being dying from this cold.
So, it sparked the question in my mind. Why is it so often depicted that a person in say, 1830, gets sick and it's pretty much curtains for them.
Now, again, obviously, there are other things to consider. I most likely won't need to go outside with the flu in frigid tempetures to feed livestock or be forced to travel by carriage into town to get food. I'm not likely to exacerbate the issue.
Nevertheless, is what we see in movies or books often a device simply to kill off a character? Can I just decide, hey, I need my character to die tragically before they can reach their family. I know, I'll give them the flu!
Forgive me if I miss some obvious reasons for why the flu was deadly to someone in 1850, but call it curiosity.
No, it is not inaccurate. Until the germ theory of disease was developed between 1850 and 1920, death from simple infection, childbirth, mosquito-borne disease, puncture wounds and poor sanitation was a common occurrence. Even after the development of germ theory, the lack of effective treatment meant large numbers of people continued to die of infectious diseases, leading to rates of death far higher than those today.
Let's dig deeper.
In 1812, the first issue of the New England Journal of Medicine was published. For its centenary, and again for its 200th anniversary, the NEJM published retrospectives looking at changes in medicine since its founding. One of the more fascinating items from those first issues 200-some years ago is this table of deaths showing the cause of death of all 942 people who died within the limits of the Town of Boston in 1811.
Consumption, or tuberculosis, accounts for nearly a quarter of all deaths. Three times as many people died of diarrhea than cancer. Four times as many people died of fevers as old age. Nearly as many people died of parasitic infections (worms) as drowned.
By a century later, public sanitation programs had been created. The establishment of effective sewage and drinking water systems reduced many problems previously caused by unclean living. In their place came infectious disease. In 1900, the leading causes of death were pneumonia/flu, tuberculosis, and diarrhea/enteritis. Together, these accounted for nearly a third of all deaths. The death rate per annum was nearly 1,100 people per 100,000. Today, it is about 600, and the leading causes of death are cancer and heart disease.
To observe its 200th anniversary, the NEJM created this nifty interactive graphic that allows you to chart the rises and falls of various causes of death through the 20th century. You can watch, decade by decade, as influenza and pneumonia recedes from the leading cause of death in the United States to the ninth-leading cause today. Here are the raw figures if you'd like to look at them in stead of a pretty chart.
Now, I've focused on the United States alone in answering your question. Look at similar Western countries (Canada, Britain, France, Norway, etc.) and you'll see similar patterns. Look at a country like Senegal, in West Africa, and you'll see a different pattern. There, infectious disease is still among the leading killers annually. You'll find similar trends apparent elsewhere in Africa, parts of South America and Asia.
The OP seems to be conflating his experience of the common cold with "the flu". Influenza is an entirely different group of diseases which regularly form widespread and deadly pandemics. The "Spanish Flu" of 1918 killed millions (50-100 million) of people world wide. The virus strain changes regularly, there are different vaccines each year for different strains and seasonal influenza still kills an estimated average of 36,000 Americans a year. Vaccination is recommended both for those at risk and those most likely to be exposed.
You would have been unlikely to die of a cold in 1850. Despite improved medical treatment, influenza could still kill you today.