I'm not too sure about your guess that most Americans can afford even a one time payment of a couple thousand dollars. That seems to way underestimate how impoverished many families are. To your note about GPA being easy to game, that's definitely true. The real issue is that families with means will likely always be able to game the system in some way. Testing and college admission coaches can be hired, opportunities can be acquired through family/connections, etc. I think colleges are struggling to reduce game-able metrics (like dropping the SAT), but it really feels like an almost intractable problem.