It doesn’t need to be this way. Essentially all UK universities are “public” and none operate this way. There aren’t special police forces that roam their campuses (Oxford had this for a time, but I think it was the only one). Violation of university rules is no more serious from a legal perspective than violating any other private rules.

I think campus police are an insane idea. There should obviously be a good relationship between any university and the police in their area, but the idea that they should report to the university leadership is nonsensical.