In NYC the police and firemen gave their lives to rescue people. In NOLA, there is the perception that police officially resigned and became looters.
LA has also seen police "pullout".
Then again, when protesters riot in America during any of their events, there is never much will to do any genuine prosecution for their disruption. Lock them up but later drop the charges.
It is a difficult job. Deciding that it is "not worth doing" is a bad call during a disaster.
I'm not defending the cops, but I would like to add something. Many of these cops had to make a choice between staying on the job or seeing to the safety of their own families. It's a tough choice.