An educated citizenry is a vital public good, of course. But like most such goods, a competitive and responsive private sector could do a much better job of supplying it than the public sector can.
I think THAT statement might have needed to be proved rather than merely asserted?

Reasons the private sector market mechanism will not work well in education:

(1) The consumers are ill informed and ignorant. Their choices will be even worse than they usually are.
(2) Good providers are not in fact able to upscale their operations to respond to demand for their product. Conversely bad providers are unlikely to be forced out of the market
(3) Each consumer makes only one or two purchases, each of a period of years. Its not like buying insurance where repeated purchases each year keeps the provider on its toes.

Of course if the kansas attempt to have ignorance and stupidity taught at taxpayers expense were to succeed you would have to conclude that the state government was indeed too stupid to be allowed to have anything to do with education, but that is hardly a positive case for it.