Memphis PD has a bunch of those camera trailers. I believe these are referred to as SkyCop. They can be found at city/gov owned venues around town as well as some of the larger store parking lots.
I was parked within about 100 ft of one last January when my truck was broken into.
I was involved in one of the first uses of these back in the late 90's. We took an old utility trailer, outfitted it with a camera on a telescoping pole. Had recording capability but no audio. We also monitored it
on-site in real time. meaning we were physically present actually watching the events as they happened. We usually set up at one of the malls, especially around the Christmas shopping season. Under those conditions, it was effective and we made several good arrests for auto burglary as well as assorted other lesser offenses.
Nowadays the units are more sophisticated, they have better cameras, audio, recording and are even now having gunshot detection technology added. But although they are still monitored by humans, they are miles away from the unit, not on site for immediate intervention. Incidents now are detected, evaluated, an alert is sent from the real time crime center to dispatch (miles away from the rtcc), a dispatcher has to assign the incident a priority level, find an available officer, then dispatch on it. if a higher priority call comes in, it gets pushed further down in the stack.
Because the city cut pay and benefits a few years back, over 700 officers quit and left for other departments. Subsequently, there aren't enough officers to handle the usual call load, much less the increased load generated by these things.
But the public has been buffaloed into believing that these are a necessary and acceptable alternative to an actual working cop. They are just another tool, not a substitution. Some neighborhoods are even fundraising to purchase a unit to sit full time in their area because there aren't enough officers to go around and they have been conditioned to believe that they are the future of law enforcement.