I would caution people of survivor's bias. Only saints promote people with strong different options and who act on their options. Academia is full of strong egos.
It isn't something that they are necessarily responsible for, and it is a small amount. But it is paid in their name.
And things seem to have changed. I was a postdoc 2 years ago and salaries seem to be higher (although glassdoor typically reports exit salaries).
There seemed to be a big imbalance in the late 1970s and through the 1980s (sic), and I gather it's only gotten worse as the big and successful push for cheaper science labor began in the '80s.