Show me any student accommodation provider who lets rooms at £12 per week - or rent-free - and you might be able to claw back some shreds of credibility. Otherwise, I maintain that those figures are silly.
The bottom line is that there will always be a need for 'pack 'em in, stack 'em high' micro-managed hangars for international students and first years, but most second and third years prefer to be paying a lower weekly rent in a real house, in a real community, not an characterless rabbit hutch where they are ripped off to the tune of £100+ pw. For that amount in most university cities, they can get something high end with wall mounted plasma TVs, walk-in showers, cleaner, etc. Why on earth would they opt to go back into the type of accommodation which they spent most of their first year looking forward to getting away from?
You are underestimating the rite of passage factor.
I have dreamed in my life, dreams that have stayed with me ever after, and changed my ideas; they have gone through and through me, like wine through water, and altered the colour of my mind. Emily Bronte