I've read a little on Wiki and elsewhere about US, Jap and other school systems.
This much seems evident:
*USA spends as much as Switzerland on the public school system (#1).
*Public schools have fewer teachers than private schools. Ie, there are more non-teachers, eg administrators, sports team coaches et al hired at public schools.
So it's not really the funding that is the problem.
The problem is probably how the money is being used. Too many administrators, too many football coaches... Just too many people not teaching.