If all of them said twice the price, you'd still have to pay... three times the price too. If it's something you're unable to do by yourself, and if not doing it makes it even worse, you basically have no choice. This applies in the same way to job openings.
The no-negotiating theory would just mean that employers would be fighting for women employees if they were indeed cheaper for the same work output, until the competition would bring the prices up to the men levels.
is this abusive?
the company is not your friend, it is always going to pay you as little as it can that still keeps you working there happily.
agreed that companies tend to fail to adjust comp to actually keep people happy & working there, and in many places this leads to people leaving, but this I would say is exactly because the company doesn't know you're worth more
You're right it's not a friend, however this model sets up all kinds of terrible ethical games. Am I also going to happily work for as many employers and fake as little work as possible to collect many pay checks? See the arms race we're setting up by choosing to play entirely selfishly. (Which economics would call rationally)
Of all the apologetics around pay gap, I think this is the one that many people could agree is the least fair. The company knows you're worth more, they can feasibly pay you more, they pay someone similarly skilled and talented more. But they do not simply because of a conversation at the very beginning of accepting a role (and once a year). Talk about an abusive angle. That's like saying to a child "Oh you could have got a PS5 and a game for your birthday, but you only asked for a new game for your ps4"... Employers should be seeking ways to retain talent and underpaying is a ticking timebomb.
The cost of rehiring is MASSIVE:
ad/promotion cost for the role(indeed), at least 100 hours of interview time (across candidates), 1/3rd the salary to the recruiter, 3-6 months of gradual training before they're "highly productive", losing 1-3 months of adopting team's productivity to training that person, losing the institutional knowledge of the outgoing person. Losing the opportunity of having a tenured person to promote into a higher level that is even more expensive to hire for. Not to mention the opportunity cost of the work that could have been done (eg if instead all those resources made your product better)
It's asinine to think someone would risk losing an employee over $20k when those costs above easily amount to 10x that.