[revelio]

The prevailing world view of SF and that part of California in general states that the root cause of crime is society at large, and not so much the individual criminal. In this world view a criminal is to be pitied and improved or perhaps just left alone rather than victimized by the state, not locked up.

Due to the absolute dominance of voters with this mentality, and the practice of electing prosecutorial positions that in other parts of the world would be professional appointees, they have repeatedly ended up with prosecutors that ran on a campaign of refusing to prosecute. This isn't specific to SF, it can also be seen in LA and New York. In fact one of the criticisms levelled at the Trump inditement is that the prosecutor in question campaigned specifically on prosecuting Trump (for whatever) and has now upgraded what would normally be a misdemeanor, whilst simultaneously downgrading many other types of crime.

In other words: politics, ideology, the usual suspects.