Denmark proves that vouchers are not incompatible, when combined with the other conditions which exist in Denmark, with good outcomes, but the other places that don't do it and also have good outcomes show that it is not necessary for good outcomes.
Good points. We just don't have that vacuum to test as gov's differ.
Market forces improve conditions. Motivations are realigned to the incentive of the parent's satisfaction with their kid's education. Service improves when you have competition.