Don't worry, it's a quite typical reaction at FR, - whenever facts interfere with emotion.
I support a national sales tax, but I have to disagree with you here. Of course the feds are taxing money twice if it was saved before the sales tax went into place:
Person A pays $25 on his earned $100 and saves it. After the NST, he spends his $100 on a widget costing $100 and pays another $25 in taxes. The widget costs $25 less than it used to. Person A has paid $50 in taxes but has saved $25 because of the lower widget cost.
Person B saves $100 without paying taxes. He spends his $100 on the same widget Person A bought and pays $25 in taxes. He enjoys the same lower widget cost but has paid half as much in taxes.
Any sales tax scheme will need to account for these differences. There are a ton of people with substantial Roth IRA (and other post-tax) savings that will be screwed (in relation to people without savings) under this scenario.