I asked a cop I know. What a radical idea.  She said without hesitation "SB91."  It's the broken windows theory.  You tolerate what seems petty stuff and it sends the signal that the community doesn't care and won't stand behind cops enforcing the law.

This is what drove New York City downhill years ago and they only reversed course when they started to get serious about the petty stuff.  Now recently they seemed to have made the same mistake again and guess what?  They're going downhill again.