It’s pretty cheap. Not as cheap as it once was but £9k a year for 3 years with no difficulty in getting the loan and only having to pay it back based on income level after you graduate is a pretty good deal - particularly compared with the US.
Those grads are never going to pay their loans off, so that's a 9% tax on their salary every month forever.
The only ones who can get out are those with family who can lend/gift the money to pay the loans off.
Well, 9% of your salary above £28k, and wiped 30 years after your first payment.
In any case, it means no-one is too poor to study at tertiary level (recognising that there will always be circumstances that mean someone cant') while still making everything can be funded.
It's not perfect, but no system is.
Edit: that’s what they were 10 years ago when I was a student. I’d guess it’s more expensive now.