In Italy they have Finance Police: when you buy something, you MUST hold onto the receipt until a few hundred meters away from the store. Some Italians may be able to shed more light, as I've only ever seen them operate in Rome and never in Florence or Venice.
"A 32-year-old chef in Athens says his income taxes are automatically deducted from his monthly paychecks. But every time he buys something and is given an option to pay less if he doesn’t ask for a receipt, he says yes."
[1] http://www.wsj.com/articles/greece-struggles-to-get-citizens...