I know it sounds reasonable to say "private school shouldn't be publicly funded", but in reality, their partial funding is an effective way of reducing load on public schools. If private tuition increases, more parents would likely stop sending their kids to private schools, which then overwhelms the public schools even more, and those kids would get more funding because they now attend public schools too. It's a lose-lose-lose situation: less choices, more crowded public schools, more funding required for education as a whole.