One thing I never see studied on this topic is the differing impacts of social expectations on gender roles related to how much someone is willing to work extra for extra salary. At least for the part of society where I live, a man's income influences his perceived value as a partner more than a woman's, and in general there is an expectation that a man is the provider who pays for dates. (I'm not defending this double standard at all, only say it is what I observe.) Wouldn't this create a stronger force for men to do more to increase their salary than for women?
Possibly yes, but it's too easy to create narratives like this. For example, women are more likely to become the caretakers of children and elderly parents, so they have a stronger force to ask for a higher salary now. You can't say how the factors balance out without serious research.
