I worked in a university for years, and still do from time to time.
I think that as with so much about human interaction, these things vary from person to person, and possibly course to course.
Students who get involved with societies and things like voluntary work tend to build networks and make a wide circle of friends, whilst those who turn up for classes and then go home don't. I also think that more people live at home (ie with parents) than in the past, so there is a lot more commuting, and less after-hours socialising than we did.
As a generalisation, a lot of students are very focussed on their marks and getting First Class degrees, which were very rare in the past, but are now more common. Some students feel that if they don't get a First they have wasted their time and money (which is not true, of course, but leads to a very study-driven experience, rather than an all-rounded one).
I'm not sure if there is a question in the OP, but in my experience the situation you describe is not uncommon, but if your grand-daughter wants a different experience it is easy enough to find it - it just won't come to her. If she asks about societies that would interest her in the SU it would be a good place to start meeting people to befriend. Her department might run extra-curricular groups and committees, too.