You know, the thing is, prohibition is largely responsible for drug addiction... The negative consequences of being an addict would be significantly reduced, almost to the point of being perfectly acceptable vice (like smoking cigarettes) if people no longer had to fear the government, be forced into rehabs and prisons, pay ridiculous sums of money for something that costs almost nothing to manufacture, and no longer worry about dangers from buying off criminals or dealing with the impurities used as cutting agents. That being said, Captain is spot on. They're really needs to be a large, nationalized, support system for drug addicts trying to recover (and I'm not talking about prisons, which seems to be the method the US prefers right now!) mainly by treating the underlying causes (usually depression, and other mental illness).
The thing is, addiction as a disease is still not fully accepted by everyone, even addicts. I'm sure that plenty of people would be perfectly content to be addicts all their lives as long as the consequences were minimized by ending prohibition. Of course there is also the negative stigma of being an addict. "It's your own damn fault!" "Get clean, just quit!" "You're pathetic!" These are not uncommon phrases heard by addicts. The government might not care about addicts. All that being said, there are promising signs, suboxone being a major step in the right direction (IMO). Hopefully gene therapy, in the future, will be looked into for treatment of addiction.