I don't see the sense in these surveys.
People get an email, most ignore it and some do not. Why is this so, is it because one type of student is more inclined to respond (one type of student experience is more likely to respond), from particular universities. Say you go to Teesside and you're not enjoying the course, are you more or less likely to be reading your uni emails (and therefore more likely not to see this survey requesting you to rate the uni) than the pissed off student at Oxbridge?
I remember looking at responsiveness rates, I think for NSS, and the shoddier the university is the lower the responsiveness rate is. Might it be that the 1% of students who respond from Teesside are the most involved and motivated students, and therefore are more likely to have a positive student experience? Maybe the Teesside student feels that their career prospects will be influenced by how the uni looked in rankings and has an incentive to make to soften the harshness of their critique, whereas the Oxbridge student knows their career prospects are gonna be alright and have more freedom to be honest.
You don't know what the Teesside expects, they might have expected the course to be poorly organised and found it to be adequate; you don't know what the Oxbridge student expects, likely a really high quality of teaching and support. Maybe the standards expected, and therefore the quality expressed, must be different. While I might give McDonald's 5/5 stars for getting my chicken nuggets right and for serving them without spitting in my eye, their 5/5 stars would not even be close to the quality of experience had were I giving a Michelin-starred restaurant 3/5 stars.