Some of them are just like swiping your card - e.g. they just pass the same data as a swipe in one pass and go. The other kind, AIUI, are indeed the same as th

Some of them are just like swiping your card - e.g. they just pass the same data as a swipe in one pass and go. The other kind, AIUI, are indeed the same as the chip transactions, with all that entails. e: Other posts seem to say that all the contactless transactions are offline, which means no multiple expensive round trips upstream either way, so nevermind.