It's working just fine. I guess if you want drug use to go down, or to reduce deaths etc. if those specific metrics are you goals, and nothing else matters, that's one thing. Maybe it is not "working" by those standards. But I don't want a government having any opinion on what people put into their own bodies. It is a health/medical issue and, in a broader context, a liberty issue. It is not a legal issue in my opini…
Because we invest in people. We pay money to educate them, in many cases feed, shelter, and clothe them and in a variety of other ways. We expect citizens to contribute back into society. Having millions of zombies interested in nothing else than getting high is self destructive not only for the individuals we have invested in but also to our societies general longterm health.
So yes, government does have an active interest in having a healthy populace.