You should be afraid...and you are right we have to be vigilent. SepSchool has a great link that address some of your concerns... some of their points are below or to read in its entirety click on :www.sepschool.org/misc/vouchers.html
What about tax-funded vouchers, tax credits, and charter schools?
While tax-funded vouchers, education or scholarship tax credits, and charter schools introduce sorely-needed competition into schooling, they have at least four serious flaws which outweigh their good side.
(This article will refer to vouchers. When all the camouflage is removed, these flaws are also inherent in universal tax credits, refundable tax credits, scholarship tax credits, and charter schools.)
1. Vouchers spread the dependency attitude to independent families currently paying for their children's education.
2. Vouchers obscure the difference between parents who are willing to sacrifice to send their children to a private school from those who are unwilling to sacrifice. This means private schools will lower their standards of who gets in.
3. By creating a flow of money from the state to private schools, vouchers pave a wide road for additional regulations and controls. "When you reach for the money is when they slip on the handcuffs."
A common control is to require voucher-redeeming schools to administer standardized tests. These tests, in effect, dictate the curriculum, as the private schools do not wish to have lower test scores than the "public" schools.
4. Other than expensive prep schools, private and religious schools that refuse to accept the voucher will lose a significant number of their students to voucher-redeeming schools. Many will face the choice of accepting the voucher and its controls or going out of business.
The net result of these flaws is that private and religious schools will become more and more like the "public" schools. In effect, vouchers and other schemes of using tax funds for education will kill the goose that is laying the golden eggs of private education.