Blameless car fault reporting

It must happen at least three times a day that I'm driving behind another car and say to myself "He's got a dud brake light which he probably doesn't know about because he never drives behind his own car, and I have no way of telling him about it". So he drives around with a dodgy brake light until some poor mug runs into the back of him. Of course I *could* report him to the police but that would get him into trouble and seems like a huge over-reaction. What about some organisation you could ring up and say "[vehicle number] has a dud left hand brake light", who would then immediately whisk a message off to the vehicle owner alerting them to the problem. Just that. They wouldn't be law enforcers, just problem reporters. It would have to be run by people seen as the "motorist's friend". Maybe the motor manufacturers? Breakdown recovery companies? Not the insurance companies, certainly.