Also, there is a silly fantasy that the cop will find a gun on the ground, run the serial number and know who the killer is. In reality, that only does two things, the cop finds out who the gun was stolen from, and they generate a chain of custody from who bought the gun knew until it got somewhere else. Nothing comes of it.
The only other thing they’ve used it for is picking them up at the scene of cartel gun battles and tracing them back to the fast and furious ATF gun store in the United States to try to discredit American gun owners.
“Also, there is a silly fantasy that the cop will find a gun on the ground, run the serial number and know who the killer is”
Yeah, that narrative was introduced by Hollywood (probably at the behest of the government—even back decades ago). I believe it was done in order to push the belief that every gun is registered or should be. If you go back and look at old shows such as Dragnet, they immediately track the murder weapon to the owner because all guns are registered.