If the company still paid good money, then it just means that they were a really profitable enterprise.
It's like if a company like Google which currently pays top dollar, decides to pay average market salary, but loads the compensation offer with perks and time off, then I bet people would be saying that Google is a profitable company because it gives employees all these perks, whereas Google gives all these benefits because it's a hugely profitable company.
Some people would rather get paid more (especially if they are young) then work comfortably, maybe it's too hard for you to believe but America is full of people like that.
This assumes that productivity is constant per hour worked, which is far from the truth for many professions. For most professions you the productivity delta not only decreases with too many hours, it even eventually becomes negative. There's no reason to suspect that eight is the optimal number of hours for every profession; it's just a historical quirk left over from the days of predominantly manual factory labor.
Even in white collar that's not true. For creative problem solving it mostly holds but it doesn't hold very well in situations where the immediate product that isn't cutting edge and/or isn't mostly aesthetic (basically the artsy people and the R&D people). For everything else there's a pretty direct relationship between time and productivity.
People aren't machines.
It isn't, but productivity also isn't an inverse function of number of hours worked.
At best, productivity is a function of the incentives which drives you, to a limit, after which it comes down for the number of hours worked.
Take for example there are many people who had high paying corporate job, but once they quit it and started working on their own startup, despite the long hours they worked, their productivity went up.
Similarly, other people work for money, because that's what drives them.
The main point is that there is no one size fits all solution. But nearly all these studies about workplace hours studies fail to see that.
They found production was maximized with an 8 hour day, interspersed with occasional longer days.
6 hour days would be a huge boon to my personal life, but I couldn't afford to be paid 25% less. even if I was 10% more productive (probably generous), i still couldnt afford to be paid 17.5% less
One possible downside is that not everything you work on makes it to the market and you have to be proactive in keeping your skills and knowledge up-to-date and to remain employable for your next job.
Here's the thing, though. We don't even get a choice. I tried for YEARS to engineer a long-term part-time career in the software industry, and I couldn't get it to happen. I'm perfectly happy to trade more free time for less money, but there are just no takers out there. The industry isn't interested.
What I wanted is 20-25 hours per week indefinitely (and with job security).