^^ you are aware that the point of contact in smart card transactions is to limit the transmission to a small distance so people can't "scan" you CC info from your pocket.
So - in order to use a non-magnetic strip smartcard you have to maintain close proximity until the data is read/transfered.
IR type coms is the same - you need to maintain line of site comms until the tranfer is complete.
Wireless would require "in range" comms be maintained until the transfer is complete.
Seems the task of placing one device against the other is the simplest and easiest way to expedite this maintained connection.
Oh - and antoher thing - wireless PDA's have been out for an aweful long time, and are still the toys of a few - they didn't exactly conquer the world as they were supposed to - they are still too wieldy, clumsy and offer nothing more or better than any other existing technology..
I mean if they can do the job of the laptop and cell phon e- why haven't they displaced them.