The wage gap myth

Women earn less than men in the same job at the same hourly wage with the same union benefits because they choose to. Yes. With everything else the same, the paycheck is less because men work more overtime. And on a broader scale, men take the jobs with more risk, and they are more willing to move where the better jobs are. A study of librarians over 20 years ago showed that--men moved more often and had more publications. For over a decade, more women have been graduating from college, but not in the same fields as men. There are limited opportunities for dance majors and art historians. In the trades, there are wonderful opportunities, but women aren't flocking there--don't want to mess up the manicure. We live in a competitive, capitalist country (except where the government interferes) and if the CEO can make more money hiring qualified women, she will do it.

https://legalinsurrection.com/2018/12/harvard-study-confirms-the-gender-wage-gap-is-just-a-myth/

Many college grads are underemployed

Many college grads are underemployed in first job, and still underemployed five years later. Look at the chart--the highest underemployment (doesn't require a college degree) is in many of the fields women flock to, and then they wonder why there's a wage gap
  
Remember, there are reasons to choose a lower level job.  I was a secretary in the Russian Area Center in Urbana, Illinois because I couldn’t get a teaching job in Urbana (at that time you could be denied a job if you had a young child).  Some women choose a lower level job not requiring a college degree so they can have more flexibility.