Loud noises can startle people, some zones are marked as “no loud sounds” i.e. hospitals and they scare off fauna. Imagine driving through the forrest and spooking an animal that then goes after a guy that is on a walk. Or imagine the same thing in a public park with peoples’ dogs. I had my catalytic converter stolen a few years ago and it caused the nearby parked cars to turn on their alarms when I started it. Then there is obviously hearing loss from loud noises. There is also a risk of the exhaust failing further, detaching and hitting another car.

Honestly it doesn’t surprise me that the guy gets stopped by cops every time. It’s not something that you don’t notice when it drives next to you.