Why a student should pay a graduate tax on top?

The linked mini-article at ‘A Fistful of Euros’ goes to show how wrong the British Government got it with regards to the tuition fees at British universities. It’s one thing to argue that higher-quality education can only be the product of additional private funding of universities, as opposed to public funding which — as in many other parts of Europe — is being reduced, and another to argue that profit should be made out of the loans students take to fund their studies. Both make little sense to me, but the latter makes no sense at all, besides being totally unfair for those borrowing money to study.