[stickfigure]

All forms of crime are not fungible. Drug prohibition is hard to enforce because none of the parties involved object to the transaction. Extortion rackets are not scalable - at least one party is inclined to look at law enforcement as the hero in the story. Corruption isn't something you just set up on a street corner. Prostitution isn't that big of a business and at the end of the day, the prostitutes really don't need you. Gambling is already legal pretty much anywhere there's an Indian reservation (here in the US, at any rate).

The criminal class may not go away immediately, but you can take away most of their income. No other form of crime is as lucrative. Drugs really are special.