Comment by tialaramex

That's usually just because it's the same network, it's not a loss of isolation.

It is possible for your university to run a single WiFi network that is multi-campus, and so some "local" packets have to be sent between campuses, whether that's a good idea doesn't necessarily affect whether it's how it was set up.

If your university has campuses in other countries (as mine does) it is not likely they use a single WiFi LAN though it isn't impossible. However the fact that the networks operated by UCLA, Manchester University and the Sorbonne are all named "eduroam" is just for the pragmatic reason that WiFi devices connect by name, those aren't the same WiFI LANs, any more than the guy I know named "Steve Harris" is the bassist from Iron Maiden just because they share the same name.

[The Eduroam name has more significance than the coincidence of name, but that's all the name is doing here, WiFi devices which trust your local cafe "Coffee WiFi" will also connect to the "Coffee WiFi" offered in a completely different store.]