It's simple. When the supply vastly outpaces demand, it opens up many doors for exploiting those lower on the ladder. Both grad school and classical music are 2 such areas.
Software Engineering still hasn't reached that point. The profits earned by having top percentile employees, far outpace the compensation packages they demand.
A decent software developer might be worth three to five mediocre ones, without being particularly valuable. The idea of the 10x developer is so overwrought, but there are just so damned many people who are not capable of producing anything at all.
It's really a profession that does not scale well.
Software Engineering still hasn't reached that point. The profits earned by having top percentile employees, far outpace the compensation packages they demand.