I don’t know what things are like today (this was 2008), but expulsion didn’t happen unless a student committed violence against another student. Suspension was also very rare, only in extreme cases. Every student who didn’t fill those seats became a budgetary penalty. If we didn’t fill the seats, we didn’t get our money. That’s the way it was in the days after the economic collapse. We literally couldn’t afford to suspend or expel students so unless they committed physical violence, the only thing we could do was give them detention (which they never showed up for). This is one of the reasons I left the profession.