Thanks for the clarification.
You’re right, a national sales tax is not the same as a VAT. I’d still worry about abuse of a national sales tax (and most especially if the donkeys tried to use it as a gateway to a VAT), but still a national sales tax is a whole lot more palatable than a VAT.
The same political and economic pressure that prevents the Congress from simply hiking tax rates when ever it feels like now, would apply to even a great extent in a 9-9-9 system.
Everyone pays so everyone knows any tax hike means they pay more. Under 9-9-9 the is no more illusion that someone else is paying for your "help" from the Government