The use of RFID technology for identification and sales has been increasing tremendously. One area that I have worked in is public transit. Many transit systems are using cards with RFID chips for their monthly or weekly passes. One major challenge here is to check information on cancelled passes at the point of control and to block the pass if necessary. Some transit systems also have purses on their cards that can be loaded at ticket machines or by a bus driver.
For all these transactions and often also for each ticket use data records have to be stored and transmitted to a central database. This can then be used for distribution of fare revenues. For these data transfers different protocolls are used in different countries. I have extensive experience with VDV-KA which is the standard in Germany.