There are thousands of small mom and pop sellers with an Internet presence. Now they are saddled with a nightmarish task of determining the correct sales tax for any state they sell to, collecting that tax, then remitting it to the individual states. You can't believe this isn't going to be a costly affair for them. I can picture many sellers giving up due to the headache and expense.
Fair or not I won't debate, but it's going to cause a lot of pain. Have not studied it enough to know if used items will be exempt and will private sellers get caught up in it (thinking eBay)?