You are right. This will require a fee to be added on to brick and motar store sales so everything is fair.
You don't think the brick/mortar store owners will figure this out?
Prices will go up for everyone, when the "brickies" figure out they can charge more and still be competitive with mail order.
Meanwhile, outfits like Amazon brought this on themselves by blatantly flaunting the law: they have regional warehouses throughout the country from which they ship, but pretend they don't need to collect taxes for sales in the states where they're located.