That's how markets work
That's how economics-textbook idealized markets work. In the real world, many things that can be modelled as market transactions don't behave exactly like economics-textbook market transactions. For instance, sometimes people leave money on the table in an attempt to behave ethically ("I'm not going to pay her less just because she's a woman and other companies will offer her less!") or out of prejudice ("That may be her notional market price, but I just don't trust women to be good team players -- she'll be wanting to leave to have babies or something") or for any number of other reasons.
CellBioGuy isn't (so far as I can tell) trying to force employers to pay women the same as they pay men (that would count as "demanding" and might be unethical); he's merely saying that he thinks they should pay women the same as they pay men. Do you really think there is an ethical problem with saying that? (Er, of course you might disagree, but it looks as if you're saying more than that: that CellBioGuy is doing something unethical merely by expressing that opinion.)
In some situations that fit this general pattern -- things are bad for some group (in this case: women), and someone else has an opportunity to take advantage of their difficult situation in a way that actually helps them a little (in this case: employers who can pay them the going rate and thereby get cheaper employees) -- it's clearly reasonable to say "Yeah, this looks bad but actually these people are helping this group and all the blame, if any, should go to whoever is responsible for the group's bad situation." But here what causes the bad situation is exactly all those employers who choose to pay women less than men whose work is equally valuable to them, and an employer who takes advantage of the situation by paying women exactly the market rate and merely hiring more of them is part of the problem. (Slightly less so than the other employers who aren't even preferring to hire women in this situation. But still, part of the problem.)
It seems to me that the argument you're employing here can be used to defend the continuation of absolutely any sort of pay inequality. If somehow a society gets into a state where people with blond hair are paid 20% less than everyone else for equivalent work, then that 20%-lower figure is the market price, and offering more than that would be (in your terms) "a gift", and so -- if your argument is right -- it would be wrong (not merely incorrect, but unethical) to say that employers really shouldn't be paying blond-haired people 20% less than everyone else. That seems to me like the sort of conclusion that constitutes a reductio ad absurdum of the argument; do you disagree?
CellBioGuy isn't (so far as I can tell) trying to force employers to pay women the same as they pay men (that would count as "demanding" and might be unethical); he's merely saying that he thinks they should pay women the same as they pay men.
Not really. If an employer only hires women than it's not about paying woman as much as the employer pays men. There no real reason why the employer who only hires woman should pay them as much as a men would get if he worked for someone else.
If a men applies to the company and is willing to work for the kind of wage women usually get in the market place of course he could be hired.
LW readers have unusual views on many subjects. Efficient Market Hypothesis notwithstanding, many of these are probably alien to most people in finance. So it's plausible they might have implications that are not yet fully integrated into current asset prices. And if you rightfully believe something that most people do not believe, you should be able to make money off that.
Here's an example for a different group. Feminists believe that women are paid less than men for no good economic reason. If this is the case, feminists should invest in companies that hire many women, and short those which hire few women, to take advantage of the cheaper labour costs. And I can think of examples for groups like Socialists, Neoreactionaries, etc. - cases where their positive beliefs have strong implications for economic predictions. But I struggle to think of such ones for LessWrong, which is why I am asking you. Can you think of any unusual LW-type beliefs that have strong economic implications (say over the next 1-3 years)?
Wei Dai has previously commented on a similar phenomena, but I'm interested in a wider class of phenomena.