Any time the state interferes in the market, there is an opportunity for the “black” market. Bans, taxes and regulation are usually the culprits. In the US cigarette smuggling and black marketing was a favorite. Trucks brought full truck loads of them in the Southeast, where tobacco was grown, and go to the high tax states and sell them at just under the taxed price. Lots of money in one truckload! Now they are trying to do it to oil. Lol