The politicians will figure out a way to use any tax system for leverage and political gain. Never underestimate the evil genius of politicians!

I expect they'll capture a national sales tax system the usual way. A perfectly flat sales tax won't fly politically because it's a disproportionate burden on lower income people, so it'll have exceptions for staple food, basic housing, cheap transportation, etc. Declaring categories of goods tax-exempt is easier to administer than a system of credits and deductions on the tax form because that can be done at the point-of-sale using simple SKU lookup tables. If it were done in the tax form, we'd end up having to document income to get the breaks, thus wiping out one of the blessed improvements of a national sales tax: April 15th becomes just another day on the calendar.

So somebody will get to define which goods get taxed at what rate, and therein is to be found The Power. As it has always been, so shall it always be, forever and ever, amen.

Which is to say, I think a national sales tax is a fine idea. We'll just have to live with it not being as pure and perfect as its advocates dream it will be. Nothing ever is, in the real world.