I understand it just fine, perhaps you don't. An item that costs $100 pretax under the fairtax ends up being $130 with the fairtax. 99.9999999% of the people on this planet call that a 30% tax. The fairtax folks call that a 23% inclusive rate (23% of 130 = 30). Or did you not understand that is what they do?
And you derive this from?
Applying a 23% sales tax to an item that cost $100 ads $23 to the item, not $30.
Utterly amazing how many FairTax critics change the plan in order to make and justify their arguments......