Here's one more thing that might be a confounding factor - taller people have higher salaries [0], and on average men are taller than women.
Maybe just a spurious correlation [1], but still interesting to think about.
0: https://www.livescience.com/5552-taller-people-earn-money.ht...
The question I would like to know is how large the height factor is to other measurable effects.
She is a co-author of one of the most comprehensive studies of the phenomenon, using United States census data from 1950 to 2000, when the share of women increased in many jobs. The study, which she conducted with Asaf Levanon, of the University of Haifa in Israel, and Paul Allison of the University of Pennsylvania, found that when women moved into occupations in large numbers, those jobs began paying less even after controlling for education, work experience, skills, race and geography.
https://www.nytimes.com/2016/03/20/upshot/as-women-take-over...
Supply and demand as well. More workers willing to do a job means the offered pay can be lower. Sellers market VS buyers market.
Pretty straightforward supply and demand.