On thinking about this a bit more after all the awesome points raised in the blog comments and on Hacker News… it occurs to me that as a consumer – I buy an item from my house, it arrives at my house – to me, the point of sale is my house. It doesn’t matter to me where the retail company’s server or headquarters are, it doesn’t matter where any sites I visited along the way happen to be physically located, what matters is where I “swiped” my credit card, and where I receive my item.
By that logic (if that might be called logic!), Amazon’s not responsible for where its affiliates happen to be. Amazon’s responsible for where its customers are and what the tax law happens to be in that location. That’s where fair competition rules are being violated with Amazon getting a free ride.
California shouldn’t be able to claim sales tax on a sale that happens between a Seattle company and a customer in Miami. But Florida should, as the competition is happening on its turf between Miami brick-and-mortar retailers and retailers all over the internet.
Thoughts?

