Well, better pension now, for sure!
Also things like fridge to keep milk in so you can have a cup of tea,
seats in the staff room! (one private school I worked for had no staff room, just a sort of tiny shared kitchen you could use, but had to stand up in, and leave if more than 5 people wanted to come in)
SLT that support you if parents are unreasonable,
no requirement to be contactable by parents on days off, a limit to the amount of cover you are asked to do in a week - my current school never asks for more than 2 cover lessons from me, and generally if possible, I am matched to subjects I know, and children I know... in private school I have had to cover Mandarin, of which I speak not one word!
In private schools too, there has been no upper limit on the number of students I can have, I remember one day having around 70 children all at once, in the sports hall, as about 4 staff were off with flu - then one child had an asthma attack, so I had to leave 69 children alone unsupervised to deal with the one. This does not happen in a state school, if staff ratio falls that low, a year group would be sent home - that NEVER happens in private school.
Also things like "oh, by the way, you are in charge of the year 5 netball team" - I know nothing about netball, and yet I am suddenly responsible for all their training, and matches, in my spare time?
Another thing that I have hated in private school is being told to buy clothes that are only used once or twice, once we were ordered to come in in blue track suits, I can't remember why - a brand new outfit - for ONE day!
And you have to go along with what parents say they want, even if it is ridiculous, one child had to have her seat facing East, or something, another needed the classroom lit with blue light. Parents want you available at 9pm to answer questions about HW, parents don't like the HW you have set, and want and argument about it at 9pm, and you have to agree to whatever demands they are making, etc
Also, the behaviour is not great. It can be OK, but you can also have to put up with a lot of snobbery, and being treated like a servant by the kids, and that sort of thing, and you are not allowed to complain about it.
And then there is things like bullying, and so on among students, you sometimes have to take the side of the better payer, whatever the child has done....
One private school I was looked down on by students, parents and some other staff because I can't speak French.
I have never been in a state school where you couldn't make a cup of tea and sit down at the end of the day!
All of that, and the pay is worse, the sick pay is worse, the unpaid leave situation is worse, the pension, of course, is now worse....
There is a lot more. I am sure, some state schools have terrible conditions, but my personal experience is that private school conditions have always been worse.