With the Wayfair ruling, any retailer not currently collecting sales tax from customers is still on the hook for those taxes starting this year, the only exemptions are for having small amounts of business in a state (like under $100k or 200 transactions yearly or something). Its state taxes, and every state is different about what and how much gets taxed, so its atrociously complicated. Any business not currently collecting probably will be sooner or later, some are probably still trying to figure out how and others may be hoping the ruling gets appealed before they have to cough up the money. It stands to reason that the biggest retailers both have nowhere to hide and the most resources to get their systems for collecting sales tax up and running the quickest