I envision a lot of stuff "falling off trucks" nationwide.
No more than today, with cash economy losses under the income tax. IRS estimates 15-20% losses there, with a 24% of gross income taxes and marginal rates as high as 43% and all that is required to evade the income tax as one person deciding not to report/file a return.
The maximum marginal rate for the NRST is 23% of purchases as opposed to gross income, and has the additional risk of requiring two persons in collusion to evade the tax, a buyer plus a seller. At that rate it a higher risk for less potential gain. One could expect better compliance with the NRST and at least no worse.
That's the only issue I have about NRST. That companies will see "higher profits" and not be motivated to really lower the price. Some would, certainly, but how soon? Granted, when people start balking at the cost plus the new tax, it would result in a downward shift. But would they go all the way down to a rate that didn't include current taxes?