My money is on better work conditions being a better investment long term. It'd reduce turnover. Less time hiring/training new employees, and the employees you keep are happier, stick around longer, and become more efficient at their job through experience.
You might have noticed that most companies don't care about these things, because it doesn't matter much for them. For software engineers or equivalent, sure it matters a lot, but for unskilled workers that needs minimal training? Then it doesn't matter much, as even today we see that basically no company cares about their minimum wage workers conditions.
I've noticed the opposite. Even when I worked retail jobs (minimum wage) in high-school and college, those employers considered morale the be an important aspect of a productive work environment.
We'd have company BBQs, random pizza days, birthday recognition (sometimes with cake), etc. They gave us the proper tools to do our jobs, including gloves/box cutters/shirts/etc. Typically if you told a manger you needed something (work related), they would get it for you. Things chugged along fairly well.
Reducing turnover was an active goal because it cost them time and money to hire and retrain new people, even for basic tasks.
OP suggested that I had "noticed" their perspective and I shared my opposing experience.
A history lesson on "we used to do things this way, but then we made a law that says we can't anymore" isn't an analysis. It just tells me that people got fed up with being overworked and lobbied for a law against it. Not that their employers were making informed decisions.
It's akin to the broken "butts-in-seats" culture that has been slowly dying. Many employers are realizing that more hours at a desk isn't always a net gain in the long term.
I have zero sympathy for Capital when they have to sacrifice Profit for Ethical/Moral treatment of Labour.