The general rule of thumb for taxes is if the company shipping to you has a physical business presence in the state you live in they're required to collect tax.
I live in VA, and Apple has a number of stores here. I pay taxes if I buy from Apple, whereas if I buy from Amazon no.
But the catch 22 is that legally in most states you are required to pay that tax even if the vendor doesn't collect it. We do that, right? 🙂