> If women on average prefer to work less hours
But do they prefer it more than men? Maybe we should be more careful about this assumption.
I am a man, and I would prefer to work less hours. Unfortunately, my options are mostly limited to full-time or nothing.
Here is how it works: suppose that both me and my wife are at a job interview, and we both say that we want a part-time job. The obvious question is "why?"
If either of us answers honestly: "because I have life and hobbies and friends, and half of the market salary for my skill range is enough to pay my bills, so I see no reason to spend most of my awake time in an office", with such attitude we are obviously not going to get the job. You are supposed to pretend that working to make someone else even richer is the highest calling in your life, more important than your family or friends or dreams or whatever, not just something you have to do to pay your bills.
Luckily, my wife has a socially acceptable excuse. I don't. Therefore, she will get the part-time job, and I will get the choice to either work full-time or try my luck elsewhere. This is not about our preferences. This is about what is socially acceptable for each of us.
In the past I tried repeatedly to get a part-time job, but it was nearly impossible. (The best deal I got was working 4 days a week for 50% of my market salary. Even that was a rare exception.) When I respond to job offers mentioning "both full-time and part-time positions available" and I mention I am interested in the part-time one, I am usually told that those are only meant for women.
So I keep working full-time, because that's the only option I got. And now people will use my "revealed preference" as a proof that this is what I really wanted. Eh.