There is a reason community colleges exist: they are the place where the sole focus is teaching students, and so they can keep prices low.
Of course, you get a somewhat worse education there, due to the fact that the people teaching are essentially similar to grade school teachers in motivation.
Additionally, another important thing to consider is that the degrees that are actually useful have to compete for professionals with industry to some extent if they want to not be left with the dregs. A professor is going to pull $150,000 a year or more in many places, because that is what they could earn elsewhere.
And yeah, then there is the administration, IT, upkeep, dorm housing, campus police, facilities, student medical coverage, and so on.
But if you really want to know... any public university will have public records. Go check. I know that my local university has only slightly increased student tuition rates, and had a massive influx of students seeking lower prices. The problem is that once the slight surge of money is distributed, they are still on the brink of fiscal collapse due to how much the state has cut funding (they lose money for every in-state student, and have to accept them anyways) and are leaking their top researchers left and right due to the incredibly low wages they pay, relatively speaking.
But seriously, go look for yourself.