Actually it's not. In the US, the 2013 budget for new currency printing is $797M. So that is $797 million dollars that is wasted on printing a physical item, A physical item that use could easily be replaced by a non-physical item (debit card, EFT etc) that shifts the cost of usage away from tax payers. "Cash" or paper currency is as antiquated concept that cost this country $8B over the course of 10 years and people who use it are fiscally irresponsible.
By the way, can I borrow a dollar? Thanks!