And those who can't afford tutoring? What about them?
Also, tutoring can't usually replicate practical elements of e.g. science and DT etc- which will go on safety grounds if classes are too big.
Last year, I had a Y7 class of 34, Y9 class of 33, a Y11 class of 32. What size class is acceptable to most parents? Once a class got over 32, I refused to do practical work with them, as I didn't have enough suitable space in the lab.
A lot of these cost increases also apply to the private sector- certainly heating bills etc do. And realistically salaries will go up in some schools if state school salaries increase. I'd expect to see school fees going up a lot over the next year, if anything, I'd expect to see students returning to state from private.
As others have said, investing in education is paid back down the road. It should be the absolute last thing facing cuts.
And despite what you think, money could be made through taxing the rich.
You might be happy to accept crap state education, but a lot of school staff are not.