One reason people don't seem to mention much is that universities, particularly research universities, act as a kind of educational industrial complex wherein the government essentially funds the universities with grant research dollars and with it comes the overhead of administration and such.

That research money gets spent largely on research, but once you hire people for those projects the university finds ways of keeping them around. More than that, buildings and such over time get built to further the research agendas of the schools, furthering the dependency on federal grant money.

So, in a sense, the bureaucracy of the federal government funds the bureaucracy of universities as well.