How the RFID technology in shops identifies customers?

How the RFID technology in shops identifies customers?
For example:
if i take a box of chocolates in store, how the RFID reader identifies it is me who has taken this product so that it can charge me with the corresponding cost in my bank account?
please help... thanks in advance..

I guess, rfid reader identify products you want to buy as you walk though a "gantry" (i.e. only you or your shopping trolley in the vicinity of the reader) . Before you are allowed to leave the shop, you will have to wave your contactless bank card and money disappears from your bank account. Its very similar to an unmanned motorway/carpark toll booth.