This was discussed ad-infinitum on the regional forum post-Colgan.

Congress will not go there, because we already have a federal minimum wage which does apply even to RLA groups.

Any airline pilot who makes less than minimum wage (based on DUTY, not flight time) can visit his local state labor board and they will force the employer to bring him up to minimum wage for the year.

You could make the case that it is a safety issue, and pilots require higher-then-minimum wage so they are not fatigued by financial stress, second jobs, commuting, etc. The problem here is that there about a zillion OTHER professions which are also safety-sensitive, which would also demand that THEY get a minumum $50K/year or whatever congress gave the pilots. Congress knows better than to go there.