Again, we're basing this on the Swiss study.
Let it be understood that the study was conducted in Zurich, where heroin was already legal in Needle Park and the problem was already out of control. The study does not show that treatment enrollments have gone down, only that they haven't risen since 1996, when heroin use in Zurich was an epidemic because of the Needle Park experiment.
So this study merely shows that treatment socialism may have, for the moment, stopped the bleeding caused by the 1987 decriminalization in Zurich.
Now, if you're comparing Switzerland to the US when you say "more successful", you're comparing apples to oranges. Switzerland isn't America. It's not even New Jersey.
It went down during some period: "They found that the incidence of heroin use dropped from 850 new users in 1990 to 150 in 2002."
Switzerland isn't America.
True ... but still the available evidence says that treatment socialism works better than criminalization socialism.