Fun to read how you (mostly) US peeps regard working parttime. I think it was mentioned earlier, but it depends on the incentives by taxes too. In the Netherlands we have a progressive tax system, so whoever earns more (i.e. works more hours, if we pressume same hourly wage) has to pay a higher percentage of income tax. I believe in the US it is actually the opposite, right? A degressive tax system. So I guess in the US it pays off to earn as much as you can over a short time period, as you get to keep increasingly more of what you're paid as you earn more. I guess that's why most US mustachians work their ass off now, to get to FIRE asap. But maybe the lack of parttime jobs forces it this way.
In NL it is considered very normal to work parttime. Actually, in some industries it's hard to acquire a fulltime position even if you wanted one (education, health care etc.). This country has the highest percentage of employed citizens in Europe (measured as working 1 hour or more per week), and also the highest degree of people working parttime (almost half of all employees work parttime, both men and women). Remarkably, us Dutch parttimers are very happy working less hours: only 3,3% wants to work more hours if available, the rest is content with their current work-life balance.
It's definitely a cultural thing here to voluntarily opt out of working 40+ hours a week - and I feel very grateful that it is! Finding a parttime position is very doable this way.
I work parttime at the moment (28 years of age), but I work 5 half days a week. I would ideally like to bring it down to 2 or 3 days eventually to have more free days on my hands. To acchieve that later on, I'm okay with working fulltime for the next few years if the chance presents itself. However, this will only be worthwhile if my hourly wage also increases, otherwise I'd just be working more to pay more taxes. And I actually really like my current job, so it would have to be a good offer to switch.