- It makes zero sense.
EDIT: What I meant to say is men go into different careers than woman and for different reasons. Usually men go after higher paying jobs (investment banking). When people compute the pay gap they dont take this into account, so they compare pay across industries (investment banking to nursing) which is meaningless, and likely is propaganda.
[0] http://www.nytimes.com/2016/03/20/upshot/as-women-take-over-...
How will the employer react to the sudden surge in applications?
Other fields mentioned either require longer hours or were simply more demanding. We can get into what are reasonable hours or demands in a separate conversation but all things equal, employers are going to pay more for someone who works longer and puts up with more demands.
For everything else, when you introduce half the working population to a field that they were once closed off to, wages are going to drop. I am not pretending that it's the only factor but a huge over supply of labor will cause wages to drop; all things equal.
Whether the preference for fewer hours is innate or learned I don't know.