People who don’t come into campus

Is it just me or are there loads of people who just don’t come into campus throughout their whole 3+ years at uni?

You’ll see them in the first week or first month of first year, and then you’ll just never see them again (maybe at graduation if you’re lucky). They won’t come in for lectures or seminars, they won’t come into the libraries to study, they won’t come in person for any practicals and group meetings, or even to meet friends (you get the gist).

I’m just thinking how do they not get clocked for zero attendance and how do they choose not make friends at uni - after all they’re paying upwards of £9k a year to get a degree and yet they aren’t making the most out of societies and other opportunities. Can someone explain why this is (btw I went to a London uni so might affect things).