I always figured you would assume the market is in equilibrium, unless you can prove it isn't by e.g. evidence of intentional discrimination, that sort of thing

I always figured you would assume the market is in equilibrium, unless you can prove it isn't by e.g. evidence of intentional discrimination, that sort of thing. In an efficient market -- a market in equilibrium (I took economics a long time ago) -- everyone earns what their labor is worth. Any wage gap in such a situation is by definition still fair: everyone is getting what they earn.