Simple supply and demand analysis shows that goods command higher prices when supply is lower.
I believe supply and demand with market rates is a much bigger factor on the average Facebook engineer salary than the quality of the engineer. For one, we are only dealing with a discrepancy on the order of 40-50%. Is a good engineer only 40-50% better than an average engineer?
They insist only on hiring those who pass their interview.
Seems to overlap with the set of good devs, but it's definitely not the entire set.
Which hey, good for them I guess.