It's worse than legal trouble. They hold your graduation until you return all library books, pay all debts, fines, and interest, etc etc.

The usual trick is to drive someone else’s car. (Mom’s or dad’s).

Depends on where you go. My college had a legitimate police department with duly authorized officers that could arrest, carry guns, etc.

This is common for public universities, for the obvious reason: they're already a branch of the state, so it makes sense for security to officially be state police.

They're often not state police, but a small police department.

Depends on the campus. At the University of Pittsburgh, campus police are an accredited law enforcement agency with jurisdiction within so many hundreds of feet of University property. Ditto for our transit police.

In my locale, "campus police" is a division of the city police department.