The market is not efficient. Even if there really was a pay gap of that magnitude, it could still persist in the short run (compare to, "in the long run we are

The market is not efficient. Even if there really was a pay gap of that magnitude, it could still persist in the short run (compare to, "in the long run we are all dead"). The wonderful thing about high-prestige fields is that nobody really knows how to measure productivity. There's also the possibility of bias in school or training programs, which would lead to differences that the labor market is not responsible for because they exist earlier in the pipeline.