if you will notice from recent history, you will find that the cia/government has been caught with it's hand in the opium jar more than once. it is a good source of control among the gangs in the hoods. if you can control the gangs you can control the fear/control on the population. you can also control the amount of crap the people will let you get away with for their safety, of course.
no need for anyone to understand or believe this, just remember it when you are on the wrong side of their guns or face down on the ground saying to yourself "they can't do this"