I suspect the reason people could better tolerate work for decades upon decades in the olden days is because the culture was different.
There wasn't overthinking or weird schedules or distance complicating the process. Our grandfather's generation worked at the local steel factory, all his friends and the men in his family worked there, everyone around you shared a similar schedule and work culture, everything was much more automatic.
I'm certain people in the past spent more time laboring than we do, the only difference was the environment it occurred in.
So is the problem now really the number of working hours, or is it that work takes up so much more of a modern person's mental real estate while being less satisfying, because it's a less prescribed, more isolated/isolating process?
The redditors aren't wrong for being unhappy, but I don't think a lot of them are able to correctly identify why they're unhappy. Not uncommon for Reddit.