I can only speak from my direct experience of Oxbridge.
I went to a small but wealthy college, Jesus. It was the kind of college where when an old Etonian came up in the year below me and kept the identity of his school very quiet indeed because it just didn't fit with the mix of state comps, grammars, and minor private schools. I chose it primarily because it guaranteed accommodation for undergraduates throughout their degree and didn't quite appreciate the tremendous practical benefits of my choice until later. As long as Oxford's tuition fees remain the same as so many other universities it's my personal opinion that Oxford represents absolutely phenomenal value for money compared to other RG universities.
There was a generous book fund which refunded 50% of the cost of any books that we needed for our courses, up to a given limit per year.
There was an incredibly well-equipped college library, open 24 hours a day, which would happily buy in texts for library stock if we needed them (I was once sent to Blackwells clutching some petty cash to buy an urgently needed book).
After living in college for the first year (which is pretty standard) we all moved into proper three and four bedroom College-owned flats for subsequent years. We paid below market rate for lovely flats in really good locations and none of us had to deal with dodgy, unscrupulous private landlords.
There was a discreetly administered and genuinely helpful hardship fund. I only found out many years later that a friend of mine had needed to access it and he is full of praise for the college's belief that no talented student should be unable to complete their studies for financial reasons.
Then the teaching - one-to-one tutorials with two different experts every week, plus a non-compulsory (in my subject) programme of lectures from world experts in their fields.
It's a very intense place and a very particular style of teaching. There are many many incredibly talented people who find that Oxford is not for them and that they are not for Oxford. But for the right people it is an extraordinary privilege, and for those on lower incomes there is so much financial help in place.