Complexity of Simplified Sales Tax

I finally just had a moment to read the background materials for a 1/20/2010 SSUTA meeting that dealt with vendor compensation for collecting state sales and use taxes. Some of the discussion questions are interesting in that I think they raise the issue of whether the SSUTA has made sales tax compliance simple enough such that Congress should allow adopting states to make remote vendors collect.

Here are a few of these discussion questions that, I think, raise additional issues beyond vendor compensation approaches.

1. "How do you determine who is a volunteer seller and who is a nexus seller initially and going forward?" I think this implies that it is not always clear when a seller has nexus in the state. And generally, that is true.
2. "Should additional compensation be required in states with more complex tax structures? What complexity factors should be considered?" Why would an adopting state's tax structure be more complex than others? If this is the case, then wouldn't it still impede interstate commerce to make a remote vendor have to collect from customers in the states with the more complex tax structures? If yes, Congress should not allow adopting states to require remote vendors to collect tax. I think this question might mean that additional simplifications are needed, such as one rate per state.

What do you think?