I've seen ads for those radio-proof wallets where someone passes a skimmer near one's wallet in one's back pocket. Kinda scary.
What bothers me about the "few feet" or "inches" range is that the range depends on the receiver sensitivity and triggering tranmitter power.
Theoretically, radio waves go out to infinity and with a highly sensitive receiver, could (again, theoretically) be picked up on Mars*. So the "few feet" or "within inches" is meaningless. If someone is sophisticated enough, one could build a triggering transmitter powerful enough to reach out, say six feet, and a receiver sensitive enough to receive a return signal from your purse or pocket.
In this respect, remember that you can lock and unlock your car with your electronic "key" from many feet away.
It basically depends on the equipment.
There's an old saying in amateur radio with respect to quality of receiving equipment: "You can't work 'em if you can't hear 'em."
The reverse of that is you can work 'em if you can hear 'em.
Terry, 230RN
* I'm ignoring signal-to-noise ratio throughout this for illustrative purposes. i'm also skimming over the fact that the return signal strength depends on the strength of the triggering signal, since that's what powers the circuitry in the card.