Because of course they REFUSE to see the benefit in crime deterrence in private carry. It would mean fewer jobs for them and less glory for their union bosses.
It's not just that, there's a fear factor and laziness. They've been brought in the land of the Sullivan law. The guys on the NYPD I know don't like going to the range. Only my best friend likes to go.
There was a robbery at a restaurant in Queens not that many years ago. The cops responded, firing over 240 rounds, IIRC, nobody was hit!