> It's not showing up in huge increases in faculty salaries, or administrative costs.Not in faculty salaries, but often in faculty headcount. Lots of colleges and universities have added a lot of faculty while keeping student headcount constant. Mostly because they can't fire their tenured humanities faculty but need to hire people who can prepare students for something other than the Barista life.
IMO: tenure should be used very sparingly and should be viewed as part of a competitive compensation package. E.g., if the CS PhDs you want to recruit all have $300K offers in industry and the best you can do is $70K-$80K even with salary inversion, then you absolutely do need to offer tenure. It's part of the comp package and you simply will not recruit good people without offsetting such significant pay gaps.
But tenure for humanities borders on fiduciary irresponsibility. The job market for humanities PhDs is such that you can hire truly top-tier candidates without committing to having another head in the Philosophy or English department 40+ years. The $50K three-year contract is a competitive offer in the humanities. No need for tenure.
> Colleges are charging more to the median student, but are using a lot of it to subsidize less well-off students.
Certainly some of that too. I expect this will be the leading cause through 2030.