how you can get a modicum of tax revenue in a cash-only society. take note, italy / greece.
China has crowdsourced tax enforcement, by potentially rewarding citizens with a cash reward for asking for all of their tax pre-payment receipts, and using them up by scratching off the prize areas. The cost of this massive force multiplier is vanishingly small, as all they are offering is the chance to win; I have only ever seen one winning ticket in the past couple of years, and it was for about 2 kuai. Still, it is a nice cultural touch to the end of a big meal, everyone sitting in a circle, scratching their fapiao to see if they won a prize for playing the part of a Chinese tax enforcement agent.