why feminist think that female dominated job pay less because of sexism?

This is something I often see. They think that teaching or nursing etc pay less because it is female dominated field. And women dominate law and med school pharmacy in many countries but thse jobs still pay good.

But in my opinion it is just about supply and demand. Teaching used to pay more when people were less educated because finding teacher back then was harder and mostly elite used to send their kids to school and elite pay more. and men left teaching because it started up having low pay. There is this expectation that men need to be main bread winner so men chose field that pay more. Even if they're hard

Same with nursing. Nurse get paid more depending on supply and demand travelling nurse make good money because there is more demand but less supply for them

I think same about trade job. In West they're only paid nicely because there is low supply but high demand for it. Go to under developed countries there men trade jobs pay almost nothing.and i am also taking living standard into account.