Previously written: "eg there are hard core libertarians who want immediate separation of school and state even to the point ofopposing a voucher system. This, I think, is impractical."
In what way is it impractical? Vouchers simply justify the government's theft of our money. We should immediatley eliminate any government spending in education and reduce taxes - possibly selling off all government education related resources and refunding the money to tax payers.
Government sponsored education usually costs quite a bit more per student than private education does - mainly because of administrative overhead. If we give vouchers that equal the average cost of a public education student, that will upset the market for private schools causing them to raise tuitions. This will screw that sector of the free market all to hell.
Why pay twice for something you could pay once with no bureaucratic skimming?