Isn't this an extension of the Laffer Curve? If government imposes too high of a tax, won't the taxpayers do whatever they can to 'beat' the tax man? States like WA and OR.... WA State imposes a sales tax and OR does not... get significant cross state traffic to beat the sales tax and merchants in WA State waive the tax on those with Oregon ID's. Doesn't the Constitution specifically deny a state the ability to restrict trade by imposing taxes on transactions that take place in another state? This should fall into the realm of competition vs monopoly. Just like TX is competing for businesses to relocate in from draconian taxing entities like CA and IL and NY, the merchants should press for lower taxes at home for all residents.