> If someone wants to pay me 1.5x or 2.0x as much for time spent on a task over 40 hours a week that seems like a very appealing prospect to me, especially if it was a task that I was otherwise going to spend my time doing for free.

Again, overtime is perfectly legal, we were just talking about the average working time per week.

> Why should the state mandate a cap on voluntary employment, rather than focus on ensuring that no one needs to work that much to survive?

Because the first one is the easiest way to ensure the later one. You are missing the power dynamic between employer and employee. That is they main point. It is just not possible for the extra work to be truly voluntarily.

It is the same principle why a boss having sex with their assistant is deeply unethical. Because the power dynamic. Even if we assistant is attracted to them. They know refusing could have consequences for their career.

Plus, that unicorn worker that wants to work more than 48 hours to make someone else rich and is otherwise a healthy, non workaholic individual, does not even exist. If someone is that driven they can just go freelancing and earn even more money.

You idea is solid in a vacuum but just doesn't work with the real power dynamics under capitalism.

> Is there any sort of data to back up the assertion that a system where people are not allowed to pay other people for more than 48 hours of their time in a week a better system that leads to better outcomes than one where people are free to exchange their time in exchange for a wage with mandatory overtime?

I mean the US has one of the worst work-life balances of any developed country, so yeah. Meanwhile Germany is pretty good in that regard. Again, most developed countries limit work time somehow.