Advanced Asian cities which combine rapid zero tolerance policing with the resulting social conformity don’t have these issues. There has been a rise in drug abuse but it tends to stay out of the public view, again due to policing.
I remember visiting nyc and seeing people shooting up in the street while the police were watching. Obviously the problem is lack of enforcement- and if petty crimes aren’t enforced even with just small punishments, then more serious crimes accelerate.
I think he's pointing out that people who commit serious crimes usually have a prior history of smaller, petty crimes that they were not given meaningful punishment for.
The data certainly supports this observation, and I can dig out supporting evidence if it's in doubt (at least in NYC, Dublin, and London. I'm not familiar with SF).
I remember visiting nyc and seeing people shooting up in the street while the police were watching. Obviously the problem is lack of enforcement- and if petty crimes aren’t enforced even with just small punishments, then more serious crimes accelerate.