If private schools have to accept anyone, we would be replicating the problems of public schools and losing the advantage of private ones, and if public schools can set entrance exams the loser students would have nowhere to go. You need a place for them. Not that they are likely to succeed any better, but that is the case now.
I don’t see the advantage in this. It’s basically price-fixing. Private schools charge more than the voucher amount are counting on parents who think the extra money is worth it. Private schools who only charge the same as the voucher attract parents who think the schools can provide a better education for the same amount, because they spend less money on discipline and extra effort for marginal students. Public schools are for the parents who claim to believe in the benefits of public education over private. Everyone gets to pick what they want.
Students with involved parents will do marginally better, because their schools will be less distracted with discipline and remedial education. Students with uninvolved parents will do marginally better, because in some cases they will be getting into a school with fewer disruptions and marginally more peer pressure to succeed instead of fucking up. And the bottom students will go to the school that accepts everyone, just like they do now. They won’t do any better, but at least they won’t drag anyone else down.
Regards,
Shodan