More states are making all students eligible for private school subsidies. In Arizona, it has often benefited wealthier families.The basic con is private schools catering to rich people increase their tuition, so the subsidy voucher doesn't cover the full amount, to make sure Those People can't afford to go.
A reasonable rule of thumb is the more the usual suspects criticize something as a benefit for the well-off, the less it actually is. Lots of silence on the real giveaways to the rich.