But that labour productivity (eg measured in salaries the market can bear) differs so much is a fact. Whether we like it or not.
That puzzle is mostly about productivity differences for tech workers. For the baristas in the Bay Area relatively standard explanations like the Baumol effect do most of the explanatory work.
This has nothing to do with people that think they deserve to work there (which I frankly don't get what the big deal is, you're not a teenager scoping out the best colleges anymore) but obviously the marketplace disagrees.
So if the best companies could employ more people in those places and pay them high salaries, those people would also pay high income taxes that could finance public infrastructure for the rest of the country.