Because working part-time you can't really advance very far in your career, and that is expected from men. From women, less so.
(As I understand it, some Scandinavian countries have brought in the legal right to paternity leave similar to maternity leave, which strikes me as a good start.)
Would a female executive marry a male who works part-time at a café?
the answer is no, it is exceedingly rare, because women marry up socioeconomically. no matter how successful a woman is, her preference is to marry someone equally or more successful.
people tend to provide extreme counter-examples to argue against this, but in the vast majority of cases, it's true.
The highly-visible counter-examples tend to come from fields with high gender imbalance, like your stereotypical doctor-nurse or boss-secretary matchups.
I think it's reasonable to posit that this effect would be weak or non-existent in an equal society.
It's not for the sake of family.
80% of employed women work part time in the Netherlands. This includes singles, double income no kids, middle aged women whose children have already left home. Only a small percentage of those working part time have young children.
When you ask them about it, they try to justify not working more. "Daycare is so expensive" (in another post I try to demonstrate that this excuse doesn't fly), "Working environment is hostile to women" etc etc.
If deep down inside people didn't feel at least a bit guilty about not working more, they wouldn't try to justify it. In reality, working part-time is a luxury. Americans prefer the luxury of a large home, two cars, air conditioning, maybe a swimming pool in the yard. Dutch people seem to prefer the luxury of few working hours and long vacations.
I don't see how a single comment can account for any/all complaints that people in the Dutch workforce might have.
Living (instead of working) is not a 'luxury', as other might say: work to live, don't live to work.
A luxury is anything beyond basic necessities like food and shelter. People in poor countries, working 12 hour work days for $10 per day or less, don't have the luxury of working part time.
I'm totally fine with someone choosing to work fewer hours or more hours than I'm willing to do, as long as they're capable of supporting themselves.
I'm not totally fine with people claiming they would like to work full time, but the government is making it impossible by not subsidizing daycare, out of some kind of conservative bias against working mothers, because that is simply a lie.