Universities also don't require the same level of 24 hour surveillance, and have a more cooperative crowd that can look after themselves. It seems reasonable to a first approximation that they would have similar costs.

In my opinion you have used a convenient generalization for prison populations which helps justify their treatment by dehumanising them. An alternative view.

Universities: 18 year olds moving out of home for the first time.

Prison Population: Many from unfortunate circumstances and have been fending for themselves long before 18.

Maybe similar costs. I don't think the major driver of Harvard pricing has anything to do with its costs though.

I don’t think campus security is responsible for keeping students on campus and organizing manhunts if they escape.

Comparing college with prison is patently ridiculeous. Why would someone expect that keeping someone incarcerated be cheap?

> Comparing college with prison is patently ridiculeous.

The point is that they are different possible futures for a given individual. The matter of which of these two possibilities comes to fruition depends on policy and on that individual's conduct. To the degree that it's determined by policy, it makes sense to restrict incarceration such that it is used at most in the limited situations in which there is societal benefit.

Drug prohibition, for example, does not achieve this, but as a policy is responsible for a huge portion of the costs of incarceration.