cutty, largely agree with the thrust of your post. It's a tax system manipulated by the elite for the elite. Just as the legal system is gamed.
Where I differ is that I see the problem as a systemic corruption of our political system. So even if the GST were to replace other taxes, it would then be gamed just as all others are. Somehow their accountants and our politicians would get together to find a way. Or would they just take the GST and hand it back in some other form to please their masters.
The core issue is gaming of our democracy, not the tax system.
