Here is my take on why they're like that. Dunno if it's true but here's my thoughts:
it's because by college or night school, most people have a group of friends - in australia, most people live at home and travel to uni - they dont stay on campus. As a result, they still live near their friends from school and have people they can do things with.
Most people consider their degree as just that - some education. They want to get in, get out and get on with their lives. They're not there to make friends, they're there to get the damn thing over with, LOL.
In my case, my degree involves a lot of roadtrips where you pretty much have to make friends or sleep in a room full of strangers, so we all know each other pretty well and put up with each other's irritating habits, haha.
Sorry to just hijack minder's thread here..but yeah. Just an insight maybe?