Chinese receipts
I kept noticing these silver scratch panels on some receipts in china and assumed they were just some form of official symbol but it turns out there actually a cunning behavioural change policy on behalf of the Chinese government.
It turns out that a lot of Chinese businesses try to dodge paying tax as asking for receipts isn’t common practise and then there is no record of what has been sold and thus no record of what tax should be paid.
So the government added these scratch panels to receipts, they are in fact a game for the public to play where they can potentially win small amounts of money, thus encouraging people to ask for a receipt.
Simple, but seemingly effective.