"Of course the easy workaround is to provide a link to Fedex, UPS, etc. and have the customer arrange their own delivery. That way the sale is local so the seller only has to deal with one tax rate and if the warehouse is in one of the five states without a sales tax it's avoided completely."
How do you reason this? The buyer is still across the state line from the seller, so the tax rules still come into play, don't they? I mean, weren't they like that in the days of the Sears catalog?