I'll jump into this touchy subject. The reason why there are not efforts to balance the other fields you mention is because of the "position of power"/"social prestige" of said jobs. I don't think anyone can debate that due to complicated social/economic issues, but significantly sexism/racism, the history of USA shows that jobs with power/prestige are usually held by white males. Oprah Winfrey crying at Obama's speech wouldn't of happened if Obama just became the first black garbage man. It was about the power/prestige of a black man being USA president. Sexism pretty much puts women as teachers & nurses and "men"(or society in general) is apparently fine with that. Road maintenance, garbage collection? Those are low-prestige & physical/dirty work. That's for minorities & men. Society(sexism) probably prevents most women from even considering those jobs and the few that do, I'm sure are greeted with an insane amount of inappropriate jokes/comments. Now, since positions of power/prestige tend to have a much greater impact on overall society, having some balance in those positions will help make products & laws more diverse to reflect the diverse society we're in. BTW, this is why I find it ridiculous the concept of exclusively men making laws on abortion.

Anecdotal: When I was a kid, I had to take some kind of "development" test to see if I was generally progressing properly. I failed that test, the results stated things such as "No solid understanding of reality vs fantasy". My parents were livid. They went to school to complain. Turns out, a lot of parents were complaining. Also turns out, all the complaining parents were foreigners. And it also turned out that the questions on the test had a heavy assumption that you were an american child with american parents. I didn't know what a pizza was when I was a kid; that's one of the questions I bombed. My parents never got it for me; at least not yet. The school ended up having to put the test-questions through some kind of minority/foreign-parents verification process and re-do the tests for everyone.