As near as I can tell, the really beautifully thought out, comprehensive legislation that was the Main Street Fairness Act and the really pathetic and awful legislation that was the Marketplace Equity Act got spliced together, with the single paragraph Section 3 A being what is left of Main Street and the rest of it being Marketplace Equity. All of the stuff in Main Street devoted to how you take a voluntary organization and essentially make it an arm of the government (how do you appeal Governing Board decisions?) is gone. You just never know how anything works out in practice, but I'm sort of suspicious this thing was designed to provide cover for bipartisan consensus around the Streamlined Sales and Use Tax Agreement (sorry I wasn't using the correct term before) that had initially hit a wall over its introduction as a bill sponsored by Democrats. I have this feeling that the Republican Senators involved in this come from states that have recently inked deals with Amazon to collect taxes and give tax incentives and blah blah bleeping blah in exchange for job creation associated with fulfillment, data, etc. centers.
But that might just be paranoia on my part.