Automated solutions are only objective on the surface. There are often baked-in-biases born from ignorance, privilege, or history. The classic recent example is facial recognition that functions poorly with people of color.
Somewhere in the nuance of programming this system will be the (known or unknown) subjective values of the programmer or those that are directing them.
Noise is quite objective. And these systems don’t just instantly hand out a fine. They usually mean you have to bring your vehicle in for inspection. If hoons have to constantly swap out the exhaust on their vehicles it would likely be enough to get the to stop doing it. Or to avoid all areas with automated detection.
It's not the bike that's a public nuisance, it's the noise produced by the bike. Making the noise as a collaborative effort doesn't make it any less of a nuisance.
Somewhere in the nuance of programming this system will be the (known or unknown) subjective values of the programmer or those that are directing them.