How would you define "work" in a way that couldn't be gamed to the point that it was meaningless?

Which is why we don't do that. One thing too many people fail to understand is that in a tax system, simplicity is a virtue because simpler systems are harder to manipulate and easier to understand. One of the reasons a lot of people like the idea of a VAT is because it's harder to game the system then our current one.

Jay