In the 1980s, professors used to print out the list of exam scores and tape it on their office door so students could check their score (something younger generations would find quaint, I'd imagine). Because people might be embarrassed by their score, they were "anonymized" by student ID rather than by name. As in your case, our student IDs were our SSNs and nobody saw a problem with it yet (I'm a bit surprised that in your school's case they were still doing it in the early 21st century, but institutional inertia, I suppose).