If somebody goes and causes an outage, I would expect nothing less than a tech walking around and trying to triangulate the offending router.

But in OP’s case, it’s an external ISP that provides internet services to the dorm. As long as nobody gives them a reason to start looking, I don’t expect a for-profit ISP to be sending out a contractor proactively beyond the first week of move-ins. That costs them money, and likely a lot more money than they would recover by catching the handful of people trying to dogde the per-device upcharge.