I think it was decided, a long time ago, around about the time of the birth of the nation. It's wrapped up in the sovereignty of the State.
By way of example, I live in Georgia. My state does not have a right tax goods and services which do not come under the jurisdiction of Georgia. Which means, when I buy products in Florida, Georgia has no rights to collect taxes from that Florida business owner, nor from me. Conversely, should I make a purchase at business in the state of Georgia, then Georgia has a right to collect a tax from that Georgia business. This is true whether the purchase is made online or not.
However, when I purchase from Amazon, a company that is not based in Georgia, then Georgia does not have the right to collect taxes from that non-Georgia business. Which means they have no rights to collect taxes from me - for I have already paid taxes to the other state.
Amazon is not based in Texas, rather they're based in Washington and pay Washington taxes - as do you, when you purchase from them. Whether or not Amazon publishes the fact that you are helping them pay their state taxes with every purchase is irrelevant - when you buy from them, you help pay their bills.
Therefore, when Texas (or any other state) obtains the rights from Washington to collect taxes in their state, then Texas will have a solid argument.
