No doubt that number is skewed by the Chicago region. School funding is dominated by property taxes; they are high in the Chicago area and significantly less in others. It is indeed a local choice being made.
This leaves the 70% in a position where it takes extreme effort to move forward. Starting a new private school system is a big effort for a position that says teachers should get 50k instead of 35k.
> Starting a new private school system is a big effort for a position that says teachers should get 50k instead of 35k.
It really isn't. Or more accurately, if it is then that is the problem rather than the salary being paid. Teaching kids to the standards of a system that is currently paying its teachers ~$35k is pretty straightforward when you get down to it; and improving on it would not be hard. The economy is made up of people continuously taking positions on these sorts of issues.
I spent decade(s) being educated, I've got a respectable number of letters I can put after my name and all the way through the capital costs outside a couple of science labs and the actual school building were negligible. And a big chunk of the important material is available online for free. Education in real terms is a really easy field to enter and compete in. But I think if anyone tried they'd just discover that people don't actually want to pay teachers money. They want someone else to pay teachers money. Because without that little rider there is only a rather small problem here to solve.
Either Illinois is in a state of poverty where parents can't afford to educate their kids, the people of Illinois don't value education. They are, in practice, signalling quite clearly that they think there are more important things teachers could be doing. It isn't that hard in principle to set up a private school, you need a building, some desks, a chalkboard and a teacher. Pay 'em what you like. I'm sure there are a lot of helpful regulations to comply with too that'll push the complexity up but it isn't that hard.
This is the families with children making choices.