Historically, it is because UK government-backed student loans (for English students: no student fees in Scotland after all) are (a) low-interest, (b) only repayable on money earned above a particular salary threshold, and (c) automatically gets written off eventually after a specified period (was 25 years, now 30 years).

(a) is arguably not really true anymore (given some graduates are paying 5% interest), but (b) is even more true now than it was under the old (Plan 1) scheme because the salary threshold is now £27,295 (compared to the old one of £19,985).

When I went to university in the UK for CS (20 years ago), my total student loan debt was close to zero. Indeed, they gave me money to study.

Even now, the cost for something like a medical degree is negligible compared to the USA where $400K for medical school and undergraduate is not unheard of. (A medical degree is an undergraduate degree in the UK)

UK student "loans" aren't dischargeable in bankruptcy either - legally they're a tax rather than a loan.

It’s not a problem anywhere, it was just an excuse for a handout to the financial industry in 2005.