We used to have a system in the uk where the addicts were prescribed drugs by government sponsored medics. It actually worked quite well, and you can give them a bonus if they get a productive job. Sadly that sort of stuff while effective at helping drug addicts tends to be an easy target for politicians wanting to be 'tough on drugs'. As well as getting addicts off the street and not killed it means less money for drug dealers so the whole thing dwindles.