Can anyone shed some light on why it seems like a number of hotels I've stayed at in Asia (previous stays at hotels in Korea and Japan come to mind in particular) want the room keycard returned or a fee will be charged. We recently ran into this situation in Seoul where we had to track down the second keycard (in my wallet ) else we would have been dinged a fee. Whereas, in North America, it seems like they're handing them out like candy; if I take the keycard home or leave them at the frontdesk it doesn't seem to be a big deal; if I forget the card in my room, no prob, here's another one.

Are the cards different in some way that makes them more expensive in Asia??