Your question belies a fundamental misunderstanding of American capitalism in the 19thC. There is a trope that the gov't was hands-off in terms of business regulation and taxation. This is completely false. There are numerous books out there that seek to eradicate this myth -- so many that destroying the myth has become a bit of a trope itself.

See, for instance, Brian Balogh, A Government Out of Sight, Steve Usselman, Regulating Railroad Innovation, and Richard Bensel, The Political Economy of American Industrialization.

That said, every business owner ever has tried to squeeze every penny out of their workers. It's certainly true that late 19thC workers had far fewer protections than some have today. It's also certainly true that many work environments were terribly dangerous and that many workers were killed in horrific accidents.

The rise of corporate capitalism and the influx of immigrants in the late 19th and early 20th Cs are intertwined deeply. American capitalism would certainly have evolved differently if there wasn't a very steady supply of nearly disposable labor. There are libraries full of books on this subject, but Sinclair's classic novel, The Jungle captures the experience well. For a more academic version of same, see Jim Barrett's Work and Community in "The Jungle."

So what? Well, it is out of this soup of labor and capitalism that more-or-less current business and labor regulation is born. Numerous movements sprang up all over the country to first assist immigrants, then to push for social and legislative change. There are so many of these groups that it's nearly impossible to catalog them all.

Out of all of this came what is known as the Progressive Era, roughly 1875 to 1920 or so. During this time, oodles of laws and regulations were put in place to try to smooth things out. Whether they were successful is the subject of a few thousand books. Some like Shel Stromquist (in Re-Inventing "The People") and Alan Dawley (in Changing the World,) see it as a time for democratic expansion -- no longer were native-born whites the only political entity that matters. Others see it as a time of a lost cause of sorts,when workers lost the opportunity to organize themselves into a massive movement that would change the fundamental nature of US cap'ism. See Nick Salvatore's classic, Eugene V. Debs, Citizen and Socialist, Andrew Cohen's The Racketeer's Progress, Robert Johnston's The Radical Middle-Class and a few thousand others for more on this take.