There are rules and a massive level of bureaucracy to distribute them. The G.I. Bill is touted as being the epitome of a voucher program. Veterans wanting to go to Grove City College found regulations accompanied their vouchers. Hillsdale College rejected the regulations attached to the G.I. Bill which were against the historic American principles of liberty. Hillsdale maintains they provide a superior education without any tax money.
Voucher plans in other states currently have minimal strings attached to gein skeptics' trust.
However, whether there will be strings attached is not the central issue in the voucher debate. The validity of civil government's role in education has been accepted for so long that people cannot imagine life any other way. Vouchers are government entitlement programs. They are established, defined and administered by government. Private schools that wish to accept vouchers should be prepared to accept regulation.