I'm not sure, when I was a student, many years ago, it was traditional to exploit the tax advantages of earning up to your allowance by working all hours flower cutting, potato picking, pea processing, etc, when you could, during the holidays. We did get grants to be students, then, of course..
Presumably 'these days' any earnings count towards the threshold of when you need to start paying back the student loan, so there is less incentive to earn any money until you can 'really' afford it
That is a totally cynical, subjective & unresearched comment, I admit, but I wonder if there is any truth in it?