If we did not mandate them by law, people could "choose" not to work at places that did not offer the above. However, that choice would probably entail "not having a job at all" which tends to be rather shitty.

My point being "it is voluntary" is not a reasonable excuse for treating lower class workers inhumanely.

That should be followed by a long discussion of what counts as "inhumane treatment". Where there is much room for disagreement still. But I don't think it is defensible to claim "they could quit" when someone else says "these conditions are inhumane and should be stopped".