I can guarantee you that if this were to be attempted in SF, they would have to have the drugs administered by medical staff. They couldn't just hand heroin and crack to the patients.
I'm not sure about the logistics, but don't think they're that complicated. Getting into those programs is tied to quite stringent conditions. Like a certain age barrier and a number of attempts to go clean. I'd wager that there's more prescribed Ritalin resold on the black market than heroin obtained through those programs.
In one sense I believe it was fundamentally successul: It turned the drug from having a "hero image" in the 70s and 80s into a complete loser drug.
Harm reduction is one of the pillars in treatment of addiction, which now is widely and generally accepted. Proven by two referendums in which the public had a say on the issue. And harm reduction is unarguably a good thing, when it comes to addiction.