>>I mean the money that government wastes keeping them in school while they are 15 and don't want to learn, can be given to them later when/if they decide to learn.

So you want to financially incentivize kids to drop out of school? "Drop out now, we'll give you a bunch of money later".

>> these are rather misguided attempts by politicians to look good, and are harmful to the society.

Saying that keeping 15 year olds out of a job is harmful to the society is....certainly a take, for sure.

>>What we do with children now is equally effective.

Well, thank you for editing this sentence from what you wrote originally, but just to be clear - I'm not advocating that misbehaving kids should be forced to sit in normal classrooms and disrupt everyone else - rather that schools should be given the resources to deal with it - the school I went to had special classes for unruly kids which were much smaller and where you basically had to meet up with specialists every week and your grades were severely impacted. It does work in most cases. Sure there will be ones that are truly beyond any kind of help - but that is very very rare. Most of the time you just have kids who could get on the straight path if someone helped them, but public schools are usually so underfunded they can't help even if they want to.