I disagree with your premise that effective law enforcement isn't a deterrent, but the trouble is that there seems to be no fair way to settle the debate. The population density in SF, vehicle ownership demographics, even the typical location and security of parking spots is radically different compared to what you'd find in other areas.

We'd need some solid numbers on converter theft rates relative to the car-owning population. But even then the numbers wouldn't be comparable, so it'll always come down to my "common sense" versus yours. My common sense says that when cops see a crime in progress and walk away whistling, it encourages further crime... and also discourages the victim from bothering to report it.