From the article:
The "voucher" program exists to give the federal government control over private schools because, whoever pays the piper, chooses the tune. Schools that accept voucher students will soon find themselves required to accept federal education regulations as well.
Obviously the government can figure out a way to screw up anything. Actually, I am not a supporter of federal vouchers, but I would like to see each state change over, on its own. Of course, it would be very important to minimize state control of the schools, at the same time.
Admittedly, it's a difficult battle to get them implemented, and to get them implemented correctly, but the stakes are high, and it's a good fight.