The most important drawback is the government would inevitably figure out solutions to these problems at the cost of my privacy.
They already have to the level of the State's satisfaction. And it is the States that administer and enforce the NRST along with their own sales taxes that they now take care of quite adequately.
The problem is the same regardless of the tax and taxes are not going away. The history of enforcement of retail sales taxes simply does not support you level of paranoia
H.R.2717
Sponsor: Rep Tauzin, W. J. (Billy)(introduced 8/2/2001)
Title: To promote freedom, fairness, and economic opportunity for families by repealing the income tax, abolishing the Internal Revenue Service, and enacting a national retail sales tax to be administered primarily by the States.
Or
H.R.2525
SPONSOR: Rep Linder, John (introduced 07/17/2001)
A bill to promote freedom, fairness, and economic opportunity by repealing the income tax and other taxes, abolishing the Internal Revenue Service, and enacting a national retail sales tax to be administered primarily by the States.