In message , Laurence Payne
writes
Because the data is on your card. Otherwise, every time you touched
in on a 'bus, the system would have to interrogate a central database
to see if you had credit.

I see. But that means that if you lose your Oyster card and report it
lost to invalidate it, anyone finding it can still use it on a bus, and
indefinitely I guess, unless the bus reader downloads numbers of lost or
stolen cards from time to time?

--
Clive Page