It's mind blowing to me that people on Hacker News don't see the absurdity of enforcing copyright law as you are suggesting. This article sums it up well:
https://www.techdirt.com/articles/20071005/094552.shtml
"The repair firm, Kwik-Fit, has a pretty weak response, saying that it's banned personal radios for ten years. Instead, it should be fighting back on the idea that this is a public performance in any way. Otherwise, you get into all sorts of trouble. If you have the windows open in your home and are listening to your legally owned music (or your TV!) and your neighbor can hear it, is that a public performance? What if you live in an apartment building with thin walls? What about when you're driving with the radio on and the windows open? What if you're in your cubicle and the folks in the cubicles around you can hear the music? At which point do we realize how silly this becomes? It's difficult to see how, with a straight face, anyone in the music industry can claim that any of these situations represents harm done to them."
Is that really the world you want? Geez.
But that's not (just) what the officer was doing - he was playing music as background to his business operation, which RIAA have definitely sued establishments over[0]. If you're playing music as a soundtrack for your business (in this case, the business of law enforcement), you need a license. Even in a non-business context, if they had a chance to sue you for playing music in public, they would. There just haven't been any prominent/worthwhile cases for them to do so. Just because it hasn't happened doesn't mean that isn't what the law allows.
[0]: https://www.frantzward.com/news-blog/june-2017/let-the-music...