Speaking about culture, women who are confident in their engagement/initiative and take charge, or simply don't let themselves get talked over, are generally seen as "bitchy" or something similar (when a man doing the same thing is seen as normal or a good trait). Women being not allowed to "speak out of place" has morphed into it being seen as bad when they're dominant or demand anything, even respect; they're expected to fit a certain archetype of being submissive or extraordinarily "pleasing" to the others (especially men) they work with. Women are talked over all the time in meetings, but it'd be a problem if they expressed issue with that or if they talked over others.

Even superiors who are women will often refuse to give other equally-performing (or even better-performing) women employees raises because of the non-explicit but powerful social pressure of male peers, or how it would reflect on them to their male peers. Society encourages "competition".

My elaboration of your comment would be that "two people who are otherwise the same that have different external traits may be seen as having unequally agreeability, and therefore, have unequal mobility in a given hierarchy", which conveniently applies to more than just gender and sex but anything else that affects appearance (body shape & color, voice, even clothing/cultural presentation to an extent), although I'd say in the workplace sex is more important than other "innate" characteristics (ethnicity/name discrimination might be up there though); but that doesn't roll off the tongue...