//it's a question about whether you see university education is a privilege for the individual (in which case students paying fees is quite reasonable) or an investment for society, in which case society as a whole should foot the bill//
No, that's not (or ought not) be the question, Jim. We all believe in higher education; what we don't all believe in is that sending any arbitrary percentage of our youth (50% in this case), for any arbitrary number of years (at the moment three) and studying any arbitrary degree course is obviously a good thing.
Examine the premise: if 50% is necessarily a "good thing", then isn't 75%, or 99% better? And if not, why not?
If three years enhances a student's utility (by dint of qualifications and training), then wouldn't six years add even more? And if not, why not?
But, whatever the right percentage or number is, isn't there some point (assuming that society wants at some stage get a return on its "investment") when the (by now) highly trained and qualified potential benefactor now becomes an actual one by leaving university and getting a job?
If you accept that the pay-off (from the investor's point of view) is useful work, then what's this 50% all about apart from dogma? If somebody is capable of contributing usefully to society by leaving school at sixteen and learning to be a plumber (as I see now has been suggested by Togo), in what way is she and society helped by keeping her in higher education for a further five years doing media studies, history of art or the pre-Akkadian history of Mesopotamia?