The proper solution is to put the onus on the payment networks. They're large enough to build out support for this issue without it being overly burdensome. Internet retailers should only be required to report what customers bought and whether taxes were collected. Then payment networks can report to the states who can send taxpayers a report of the use taxes they owe.
How about putting the onus on the party that wants to collect money off transactions between other parties. If a government wants a cut, they can make it reasonably easy to comply or they can get ignored.
