Ok so I just thought.
In a Drug Rehab center. Of course there are drug addicts and recovering drug addicts. Their mind and bodies are physically and mentally craving for the drugs otherwise they go insane right?
But we know they cannot be made to quit cold turkey. They have to gradually decrease their intake until they can manage to live without it.
This means: The center MUST have a constant supply of drugs at hand at all times for the daily needs of the patients. Which leads me to another thought: where are they getting the illegal drugs? Are they buying it? Is it being manufactured?