Amazon is "voluntarily" collecting sales taxes for several states they have no presence in. All the brick and mortar stores are complaining that Amazon and similar online stores have an unfair advantage by not charging sales tax and there are currently two bills in congress to force any "mail order" retailer to charge the customer's state sales tax if their sales exceed $500K a year. Amazon is actually wanting this, then they can set up same day delivery warehouses in every state.
Why Amazon Wants To Pay Sales Tax - Slashdot