Its odd for sure, the way the laws are getting written, Amazon and Ebay are sales portals, so that makes them liable to collect taxes, where as if it was just my sales totals, I would not qualify to remit in many states as the threshold is rather large to meet the amount of sales to have to remit if I do not have a warehouse or physical location in a particular state.
The states are making considerably more sales tax revenue. Would imagine the other 16 states are going to fall in line pretty quickly.