Cost of education versus tuition

I’m surprised the cost spread is that great among LACs.
A full professor at Carleton makes about 50% more than a full professor at U of M - Morris (not 4x more).
Average class sizes at Carleton and U of M - Morris don’t seem to be all that different.
The difference isn’t all that great in the percentage of instructors who are full-time with PhDs (85% at Morris v. 97% at Carleton.)