So we should ban every personal choice with negative externalities? There goes alcohol, twinkies, contact sports, driving, etc. It's a personal choice as much as anything else, so just estimate the cost of any negative externalities and cover that through taxation.
> Yet, a casual stroll through San Francisco 's mission district would tell you that this is not the case.
Of course you don't know any of those people and can't say for sure whether drug abuse is what lead them to the behavior that you disapprove of.
> But when I compare the outcomes of Japan/ Singapore to that of the US, it is simple to see which model is the best.
The model of inhumane prisons and death sentences? Actually the US has a pretty similar model to that already, so I'm not sure what your point is.