But they need a camera to grab the license plate of the offending vehicle…

I’m not sure if this a joke. Noise cameras are a real thing. They use an array of microphones to show which parts of an image are emitting sound and at what level.

I read it as being a riff off of “speed” cameras, which are obviously cameras triggered by speed and not cameras that capture the concept of speed on film.

I think the cameras are supposed to be triggered by noise