I don't want to go over old ground so I'll try a different tack. It sees that when this issue is discussed, people often confuse/conflate/blur (deliberately, in some cases) two quite separate things:
(1)Their ethical or principled objection to a state-controlled education
and
(2)The availability of/ability to obtain an alternative.
It rarely seems to cross their mind that the purchasing of the alternative depends only a little bit on (1), but, practically, for most people, in great part on (2).
There are quite good arguments for there being "independent", non-centralised, specialised education in this country. And there are very good arguments for it never depending on the parent's ability to pay.
I would also reiterate (said it before but never mind) that the signal-to-noise ratio on this topic is vastly disproportionate on here. If you jumped into one of these threads at random you'd get the idea that the population was divided roughly 50-50 between those who use state education and those who know better and have "chosen" something else, as if it were a matter of those who like tea versus those who like coffee. The truth could not be much more different.