You're naive if you think that the type of enforcement you'll get with a Fair Tax won't be far more intrusive than the existing system. The very assertion commonly made on this thread to that it captures everybody's expenses displays the level of comprehensive enforcement envisioned.
Unfortunately, most of the evasion will be done by low-income people who now pay no income taxes. Paying nearly 50% on a transaction (as they would in California) is a LOT of money to them (the law of the diminishing marginal value of money being what it is). So this law will criminalize vast numbers of people who now face no such complications.
Worse, for you to make such a hand-wave assertion of "far less bartering," when I cited an existing example of bootleg cigarettes and alcohol, begs for an example. You offered none. I promise you, the majority of people in this country don't worry about 67,500 pages. They fill out a short form or an EZ.
I was an NRST advocate long before there was a Fair Tax proposal. No more. Cut spending. That's the real problem.