This is Greece and they have applied the measure to stop the exodus of funds over its borders.
20,000 Euro's in a German bank will still be worth 20,000 Euro's when the Greek banks go down. the same 20,000 in a Greek bank will be seriously devalued against the New Drachma or whatever else it is they introduce.
Westonman makes an important point the ultimate aim of any Government will be to eradicate barter currency. If they could get away with it they would do it tomorrow as at a stroke it stops tax evasion (only by the little people though the likes of Starbucks and other corporates will still be ok) and makes populations far easier to handle.
An important weapon of them curtailing serious social unrest would be to close the banks for a day or two stopping (easy) access to cash, possibly even disabling the card payment networks, as and when we get the next Sterling crisis this will be one of their first reactions. Last time was when RBS went bust and the time before that when we were forced out of the ERM. They came within a few hours of enforcing Bank Holidays.
From there it is an easy step to deduct tax and other payments at source from personal accounts, for example people may not be allowed to fall behind with mortgage payments and a future Government may give banks the power to deduct direct. Without cash this would be simple and individuals would have no means of redress, or accessing their funds in any other way.
Other Governments around the World including the USA have 'requisitioned wealth' from its citizens, Argentina more recently. In fact all the gold in Fort Knox in the USA used to belong to the people before executive order 6102.
http://en.wikipedia.org/wiki/Executive_Order_6102So this isn't about inconveniencing people in having to pay for small items with a card or a NFC enabled phone there are far more dark reasons as to why they would want this.