plerdsus's post reminds me of the joke abut taxing penis length
http://www.ebaumsworld.com/jokes/read/80770698
(although the penis length tax is much better thought through).

Rhrosty, nearly all shops accept cash, and withdrawing and reissuing money is expensive. And the cash economy would probably get around it by using US dollars instead. But being easily dodgeable is the least of your problems. It's also economically crippling, making currently viable business activity unprofitable. And it's grossly unfair, restricting what people can do with their own money and placing too much of a tax burden on those who can least afford to pay it.