I can understand that TfL might be worried that people would pass their
"transfers" to friends or even sell them, although, for some reason, this
doesn't seem to worry bus operators in North America. But with my Oyster
card, this could be done automatically - no paper ticket, so nothing to pass
on to someone else, no risk of misuse. If they can do "daily capping" with
Oyster, they could do transfers. It seems that it's just tradition that
stops them.


Transfer functionality is apparently built into Oyster Prepay and used
with transfers to and from the Tramlink feeder buses and the trams.