I'm glad you recognize that you're participating in unsubstantiated claims, because that is most of the literature in support of vouchers.

Vouchers sound good if you don't think about it with any real veracity or intellectually serious rigor, but (in America) are basically a shitty partisan scam. They're basically universally used as a method to divert tax funds to schools that would otherwise be unfundable via taxes (eg. religious or discriminatory).

Why do we think parents are actually capable of choosing the "best" option, and why wouldn't 100% of parents choose that option? Parents are famously bad at making decisions, as illustrated by home schooling, religious dogmatism in private schools, parents trying to opt-out their students from scientific and health education, and the general history of parental intervention in public schools.

Why would some schools take $X per student and generate better outcomes than others? They won't and the secret is that private schools will charge more than the voucher price to produce better outcomes, but then you've essentially drained the funding of a public good to subsidize a private school that some students won't be able to attend.

As a thought experiment, can we use a voucher system to fund alternative fire or police departments? Can I apply my voucher to an FDA with a properly credentialed head? Or are schools the only "monopoly" run by the government we should break up.

> Why do we think parents are actually capable of choosing the "best" option, and why wouldn't 100% of parents choose that option?

It seems obvious that vouchers could be spent at schools that have entrance exams and don't let students in just because their parents choose the school.