I would argue that you're not thinking about working hours at a high enough level. The notion that someone can tell you that the negotiation for labor exchange is hourly is just simplifying the negotiation. For example, I make $70 an hour after you calculate it annually, but I'm not an hourly employee. I also work from home, which is a net positive because I'm a more laborious worker when I do this which is a benefit to the employer, and it's a stress reducer for me, which is a benefit to me, the employee.
But there's a secondary aspect of this situation which is that I do not have someone else "watching" me and making sure I'm working all the time. That concept is antiquated. It isn't that there's X amount of hours of work to do in a day, it's that there's Y amount of labor that needs to be done, but we don't know what that Y variable is. We fundamentally understand the overarching goal - it might be something like, how can we increase efficiency? But it's a problem solving concept where we need to utilize time (labor) to think up strategies to how we can solve that problem while connecting objective information to those strategies so we can better understand how they can even be implemented.
After all, if I can increase my own efficiency by 5% but doing so requires 6 months of my time, that isn't going to have a payoff for many years and is likely not in the best interest of either myself or the business.
In addition, working more hours doesn't correlate to more work getting done. One man might push a boulder up a hill in 8 hours while another might be able to do it in 6, or even 4. Do you want to pay them both the same amount? Would you want to be paid the same amount if you were the man pushing the boulder in 4 hours as the man pushing in 8? Of course not.
And do you always receive additional reward each time your labor correlates to some kind of improvement? Well no, of course not. Sometimes you do, and sometimes you can go years without seeing anything outside of your salary. The reason is simply because life and human relationships and interactions are complicated and there's a lot more going on than you're going to give credit for.
I make a decent income, but I also have to prove my value to my company. What I do can be in no small part measured, so if I'm not producing value, the business won't want to keep me on the payroll, and if someone cheaper - thus, less credentialed/experienced - can do much of, or even all of the value I can provide, they will just swap me out for that person, and rightly so. Wouldn't you leave a company who's only paying you $40 an hour for work that another would pay you $70 for?
Most of the people complaining about why we still have to work so much isn't seeing the bigger picture, and likely works a shitty job where the average employee needs to be monitored and probably doesn't have the expertise to be doing anything that isn't more or less transactional (meaning, you are asked to specifically perform very informed tasks like on a conveyor line). This is just a byproduct of people without high-level modern skills complaining that they're sick of pushing boulders up hills all day every day.
I mean, I haven't pushed boulders up hills for 20 years.