It depends on the societal framework. That would be anti-worker in the U.S. because you’d be sentencing some people to death, since the U.S. doesn’t have guaranteed livable wages or livable safety nets for those out of work. Given the assumption that you can make ends meet, mandating a cap on the hours spent working for someone else’s benefit and missing out on your own life is pro-human.

There is a minimum wage that's not too shabby (not good, make no mistake, but will prevent you from going hungry) and if a person is working but under the existential minimum, the government will basically put them on unemployment benefits and top up their salary to bring them up to said minimum. The system has faults, yes, and most people will do everything on their power to not be dependent on the government for that, but it will keep (cheap) food in the fridge.

Yes, people here are absolutely fine with that. You probably come from a very different world culture-wise. First of all, second jobs are not the norm here. It's rather rare, actually and most second jobs are hobbies you take money for, like photography or the like. Your employer will almost certainly not even bother to ask any further.

Secondly: your employer cannot object just because they don't like your face. There are set criteria. They will object if your second job would conflict directly with your first job, that'd be if you work at a competitor, would have work hours in your second job that conflict with those of your first job or would work too much all together. That's it.

Exactly, yes. The same goes for working more than 10hrs in a single day.

Edit: that does not apply to self-employed people. So if you work 90 hrs in your own company, that's fine.