What "different" schools allow parents to do is pull the top 1% of lucky students out to escape. Maybe most of the parents in the low cost of living areas can't give any time to their children because they've got three jobs, but there are always going to be the few that can. The same goes for a few who can one way or another afford private school. It's better that three percent get through than none.

Well, unless having the three percent get through makes it impossible to improve the condition of the other 97%. Survivorship bias is our favorite logical fallacy here in the US.

Yeah, if you reduce the number of frogs in the pot while keeping the burner setting constant, the ones remaining will boil sooner.