if the only thing stopping you from shooting up heroine or smoking crack is it's legal status then u arent worth the time(enforcing outdated laws) to save yourself from yourself...
Some people won't do things because it's against the law...no one wants te hassle of jail, court, fines, fees, attorney, having it on their record.
There is Money to be made in having a certain amount of the populace addicted, though. Think about it, why haven't they burned those poppy fields in Afghanistan? The higher ups told the military not to touch them, afghans say that is their cash crop...hmmm, you burn that and then introduce another cash crop, like tobacco or cotton, etc. They are allowed to have those poppy fields, and I wonder where the heroin goes? Also remember many of our prescription pain killers are opiate based, and drug companies make BILLIONS off of them...wonder where their suppliers come from?
Last point, remember when that pure form of heroin came out a few yrs ago, called ICE or something like that? Remember how all the the rich kids were ODing like a mofo? They took that shit off the streets quick...you didn't hear a thing about it...but as long as poor and middle class people get high it's okay. Then there are programs for them to teach them how to do it properly, money made off of rehab programs, court fines and costs, attorney and public defender fees, and so on and so forth...Drug addiction, when kept to certain populations and levels, is a money maker, and a control valve.
Remember Bruce Willis movie Last Man Standing? The Federal dude told Bruce's character, that a certain level of corruption is acceptable in town. One gang is ok, but two is not acceptable...when I come back there better be only one...