Some people going to university to study certain subjects is an economically good thing for the country as a whole. All people going to university to study any subject is not. Therefore what we'd like is some system which determines who are the economically rational people and what are the economically rational subjects.

The answer to this is to charge the people who do the degrees for their degrees. And lend them the money in the meanwhile as the average 18 year old is not obviously a good credit risk.

Thus the student loan system and here is the proof that it is working:

And there is another chilling prospect to face. The number of British 18-year-olds going to university has dipped. Increasingly, savvy school leavers are beginning to realise they are being treated as gullible customers rather than potential Nobel prize-winners or even competent linguists or mathematicians. Whatever the incentives offered, do they really want to go to university any more?

According to a report this month by the Intergenerational Fund think tank, student debt payments wipe out the benefit of higher salaries for most graduates. Politicians who use more lucrative earnings to argue for higher fees should be “challenged for gross mis-selling”, the fund says, adding that apart from Oxbridge and medical graduates there is no guaranteed graduate “earnings premium”.

People taking account of the costs and benefits of a university degree as a result of the student loan system is not a fault nor a flaw in the system. It's the point of it.