Getting rid of the job gets rid of the people with experience, so it can be a one way switch.
Normally solving a problem with a robot creates more jobs. There are speed cameras, but still you have hidden manually operated speed traps and it frees up resources for drug and alcohol testing.
Propaganda will make sure this won't even reach the average citizen.
There was an attempt to defund police, and that went down with the electorate like a lead balloon.
It's the moralizing religious right and the jackbooted ivory tower left types (both of whom think they know exactly how other people should live) that want lots of policing.
Because a capitalist economy is rooted in self-interest. Labour bodies have power to shape the economy, and they represent the interests of their members, who don't want to lose their jobs.
Plus, people are not perfect market actors with such little empathy that they are willing to abandon their colleagues for a bit more workplace efficiency. So if you know that Bob in your office will be fired due to automation, and you like Bob (and worry you are next), you're going to oppose automation.
What makes it particularly galling is that they also oppose automated enforcement of traffic laws. Officially it is because it would take away jobs (that they are not doing, since traffic enforcement in NYC leaves a lot to be desired), and unofficially because the police themselves benefit from the discretion exercised by fellow officers refusing to enforce laws on their colleagues.