Okay, here's another one:
How does this tax change affect the feds interest in controlling the borders? On one hand, they will absolutely want to stop all smuggling of OTHERWISE LEGAL goods, which represent a loss of tax revenue. On the other, illegal drugs, weapons, and other black market items can't be taxed anyway, because there is no legal sale, so who cares?
As for illegal aliens, hey, they spend money here so bring 'em in!!
They will be taxed when the spend their money at the store and when they buy their fancy cars.
The feds' interest in controlling the borders are going to be controlled by political interests, primarily those involved in attracting votes. At least the Fair Tax would put US manufacturing on a level playing field with other countries, including those to the south. Maybe this would finally persuade Mexico to reform its own socialist tax policies so its own economy could prosper. That would do more to relieve the immigration concerns than border guards or the INS will do.