> Enforcing noise nuisance is impossible in practice.

Definitely a challenge, but where there's a will there's a way.

An app for reporting would be great, though calibration might be a dealbreaker.

Just enforcing it at all would bring about a huge amount of change. I literally see police chilling in their cars while obnoxiously loud cars & motorcycles drive by and they do nothing even though my city has noise ordinance laws. The biggest problem isn’t the lack of laws but the enforcement of them. I’d wager that many of those people feel like they can get away with it not because the police will arrive too late, but because the police don’t care to enforce what’s right in front of their faces.

> Enforcing noise nuisance is impossible in practice

Just add a pair of calibrated microphones to traffic cam setups.