You make it sound like the retailer is paying this out of his own pocket!
He isn't.
The vast majority of retailers these days have computerized POS systems. Every quarter, they press (or click) a button that says you've collected $x.xx in state sales taxes. The retailer presses another button and prints a check; signs it and mails it to the state. With a NRST, the POS software gets an upgrade and the retailer has to press a total of four buttons, sign two checks, and put postage on two envelopes.
Hmm just had a thought. Retailer collects this money from customers, the people paying the tax, but the check is only paid quarterly to the government (state & federal), he puts that money into an interest bearing account that he will no longer have to pay tax on the interest.
That ought to compensate him for the trouble of having to push four buttons on his POS system.
He certainly is. If I provide a service to you worth $100, I have to pay the government $30 for the previledge of providing that service to you. If there was not a sales tax, that service would still be worth $100 to the customer. I am not simply collecting money the customer owes the government, that money is money only owed because I provided a service.