You're missing the forest fort the trees.

* Mothers are paid significantly less on average but fathers aren't and there are deep cultural dynamics that perpetuate this. There isn't a fundamental reason this should be the case.

* Women (and men obviously too but we're talking about women) are conditioned constantly from birth to have those preferences and have to deal with pressure from everyone in their lives to not deviate from what's expected from them. (Same with men too -- try being a manly man who wants to bake wedding cakes or go into fashion.) And then when women try to be mold breakers and go into "masculine fields" they're pushed away and become lower status.