How do you overcome the black market activity?

Because the things are sold "in the black" as in a secret, illegal manner.

prostitution illicit weapons

It is where goods, products, and services are sold illegally.

Of course you can the whole point of the black market is that it's illegal and when you do get arrested you will be sentenced to a long time so best to get out while you can.

Black marketing is illegal trading, so it's everywhere. A quick example: a barber must have a license. If someone without a barber license decides to give haircuts for money in his kitchen, he is a...