Arthur,
Again, I’m not denying that parents have a legitimate right to reclaim the money that is stolen from them in taxes, whether through education vouchers or through other means.
What I am saying is that voucher systems constitute a government subsidy to private schools, in virtue of forcing the parents to spend that reclaimed money within a cartel of government-approved private schools. There is nothing wrong with parents reclaiming stolen money through the voucher system, but the cartelized schools that financially benefit from federal patronage are still subject to the usual libertarian analysis and criticism offered against government subsidies.
There is no benefit that you could possibly get from a government voucher scheme that you could not get just as easily from a no-strings-attached tax break, and some specific evils that vouchers but not tax breaks would produce. So the question is, given the choice, why advocate the cockamamie transitional government scheme, rather than just advocating the simple libertarian measure?