*scratches head*
How can this (the state's actions) even be legal?
It's legal because most states don't have just a sales tax but have a sales and use tax. The use tax basically says that you are responsible for reporting and paying the tax on anything you buy if the seller doesn't collect the tax from you.
Thus, anytime, any of us order off the internet or through mail and don't report and pay tax, we are breaking state law. We've all been doing it for years. It's just the state has no way to enforce it, so they don't.
But since the cigarrette people have to report, then the states have a tool they can use.