I guess my point with this is twofold:
* Accepting Amazon's claim: this strikes me more as the removal of a rural subsidy (cheap delivery to hard to reach places, Amazon skipping out on every tax they can to lower prices) than the imposition of an urban one. Maybe a distinction without difference economically, but it's an important political distinction.
* Not accepting the claim: wouldn't this support rural bookstores? Amazon's conceit here is that people want convenience, which a local rural bookstore surely provides over an urban one for rural dwellers. Whether they "compete" with urban bookstores is sort of a red herring, given that (small) bookstores qua businesses tend to be labors of passion that aren't looking to edge out some distant urban competitor. That doesn't mean they can (or should) go broke, just that the economics aren't necessarily a dog fight between rural and urban.