WHENEVER A STATE proposes or passes an Internet sales tax bill, one of the factors adduced will be that instate bricks-and-mortars business have to collect sales tax, but that merchants exporting goods from other states do not. (This is as prescribed in the Constitution and Amazon is entirely correct in fighting these bills, which IMO, just barely miss being bills of attainder.)
Notice, too, that the state governments speak of forgoing tax revenues, as though government had a perfect right to any and all monies it can lay its hands on — lawfully or not.
And finally, also take note that the state governments in question never propose levelling the scales by providing tax relief for their native businesses. Oh, no! Can’t have that!