One of the common cited RFID use is a customer walking by checkout stand with a shopping cart.  Items in the cart are automatically noted and payment is also made automatically.  Fat chance.

Once RFID becomes common place, people will find ways to kill or replace RFID tags.  If checkout is automated, one could walk out with a cartful of expensive goods and pay nothing.

Adding a weight machine at the counter could help since a cart full of expensive wine weighs more than a pack of gum: "Please push the cart onto the blue plate and step back."  What if you had half of a watermelon and a sack of potato?  How easy is it to add weight information into RFID tags?  Sure, throw more equipment at the problem.

When all done, supermarkets will turn into US Customs.  Idle blue line leading straight to the exit, crowded red line for inspectors, and an armed guard at the exit.  So much for great shopping experiences.