In message , at 08:20:39 on Fri, 13 Apr
2012, Someone Somewhere remarked:
Whether they care or not (about getting them back), that doesn't change
the legal position wrt ownership.

Presumably they assert ownership as some way to increase the chance of
prosecution if you decide to hack "your" Oyster card?

Or if they discover dodgy behaviour going on they can invalidate and/or
confiscate cards (whilst paying back any pay as you go balance) without
you being able to accuse them of theft?

It may also be a belt-and-braces way to be able to ask to see the card,
because it's their card so they are entitled to see it (irrespective of
the general byelaws saying you have to make it available for
inspection).
--
Roland Perry