What's wrong with giving largely failed, or at best mediocre public schools some competition? And public education isn't "free." One could easily make the argument that the public money spent on the existing public education system could be put to better use. Public schools aren't any more "free" than private schools.
I wouldn't mind "competing" somewhat here, but the public schools get loaded up with more and more regulation while "alternative" schools with guv funds getting less and less every year.
Public education isn't "free" per se, but they have to take pretty much everyone as opposed to private schools who don't have to and can limit enrolment (and toher things too). I do want the private schools to keep those freedoms, not be intruded upon by government.