Money attracts taxes the same way that stink attracts flies.
I know that this is not legal, but that hasn't really slowed a state down yet. Look at what Chicago is doing, and what Rahm the dancer wants to do to all of Illinois.
Technically, there never was a "tax free" Internet. Almost every state has a Use Tax, which you are to pay a certain percentage of the amount of good you purchased out of state. I suspect states are now ramping up to start enforcing them.