counting your money

I see that US$20 bills have RFID. And so do some euro banknotes.

I don't care that much since I don't intend to visit the U.S. or use U.S. currency for much of anything (if I do, it'll be to receive payment and convert it immediately). And I doubt if I'll ever have euros in any interesting amounts.

What I do wonder is, is it going to be possible for someone walking (or someone with an RFID long range gun) to count how much money is in someone's wallet? Or if not how much exactly, at least count the number of bills there?

Do all the bills radiate the same signal? If they do, then what help would that be with respect to counterfeiting? It shouldn't be hard to create a counterfeit that would radiate the same signal (it might be too expensive today, but I bet 10 years from now it'll cost nothing). And if the bills don't all radiate the same signal (e.g., they radiate something correlated to the bill's denomination and serial number), then it might be possible to deduce how much money is in one's wallet. If it's encrypted, that won't matter much. Banks will need to know how to decrypt it, and once it's in a few hundred bank branches, one of those decrypting boxes is going to get stolen (might even get stolen during a bank robbery) and reverse engineered.

Of course, though, it wouldn't be bad, in the eyes of any government, if people were to shy away from cash transactions and go with electronic transactions instead. Taxes are easier to collect that way.