USA rules his people in mysterious ways.
en.wikipedia.org
Mortal drugs can be something useful to rule a country if it's only consumed by poor and problematic people.
It's like give weapons to criminals gangs, if they only use between them, then it's fine, and they are doing a favor to state.
Central American young criminal gangs were created in the USA and I wont be surprised if it someday will be disclosed that were created by USA undercovers. You create two criminal gangs and incite violence among them, and they make easier ruling a country if they kill each other and they dont make troubles to common people.
USA is expert creating self feedback systems to solve problems, with no mercy against state enemies.
The same can be said about cocaine traffic in the 1980s, it was useful to stop communism spread in Colombia and to kill problematic Americans in homeland.
But fentanyl is a lot more efficient in the last task.
I've seen it since young age in western poor zones, the kind of people who can cause future problems to police is the people who fall in drugs. Aggressive poor people that like to look dangerous. And often police informants offer drugs to those people and make it easily available.
I think that with electronic espionage Western states can stop drugs dealing in one day if they want, but why will they want? It's wonderful from a state point of view if criminals and potential criminals suicide themselves alone.