We do... The VAST majority of kids go through public education... It's mostly a matter of effort, and that comes down to mostly parent pressure on having their kids do the work.

Maybe if we actually held kids that can't do the work back, they wouldn't be illiterate. Let social pressure do the work it's meant to. For that matter, let parents do the work they're supposed to.

Some kids are just stupid, and it doesn't matter if they're rich or poor, there's nothing you can do about it. No need to keep everyone at the stupidest kids level.