There's a case currently in front of the employment courts here in NZ which is confronting this directly. A group of aged-care nurses (working in retirement homes etc.) have made a claim to the employment court that (a) it's a female-dominated vocation, (b) it's lower paid than other similar vocations (by demands, skills, qualifications etc) and (c) that (a) and (b) are linked.

The case has made it through preliminary hearings and is now proceeding to a higher court; if they win a massive precedent will be set, allowing for claims of gender discrimination at the level of entire industries and vocations.

(I think it's totally a fair claim.)

How is the wage level for an industry segment not related to the simple supply and demand relationship for labor in that segment?

Why is that different from reduced demand? Sexism reduces the amount people are willing to pay for the labor of the supposedly-inferior sex.

So whom should the nurses sue to recover their theoretical damages in that case?

If I decide to groom my dog myself, can I expect a lawsuit down the road for my non-consumption of professional dog grooming services if any dog groomer is a member of any minority class? After all, you can't be sure that I'm just a cheapskate who likes washing my dog; I might be racist/classist/sexist.

In case it's not clear, I view the decision to consume in a free market to be a free choice and not subject to judicial review.