Here's why it's going to fail: The plan requires participating systems to simplify their sales tax law, including a single statewide tax rate. In too many states, cities and counties have the power to add to the state tax rate to generate revenue for themselves. In California, this is about the only way for cities and counties to raise revenue. (Property taxes here are capped at 1%.)
I honestly don't have a problem with fairly assessing sales taxes. We talk about the Internet bringing us conveniences that we used to have at only great expense by earlier means. Well, that blade cuts both ways. If I drove to a vendor in Arizona to buy something, I'd have to pay sales tax on the purchase, so why should it be any different if I have it shipped to me instead? I just don't think it should be done in a way that strangles already beleaguered agencies.