We're all familiar with it - the yellow sticker on the back of commercial vehicles. If the driver isn't driving very safely or responsibly, you can call a toll-free number and report that driver. It's probably safe to assume that the driver would be briefed on any complaints. And if a driver gets an inordinate number of complaints, he might even put his career in jeopardy.
Every now and then, I have been known to call and complain about a driver - when the name of the driver's employer is plastered on the side of the vehicle in big letters. It doesn't happen often. As a matter of fact, I'd say professional drivers are typically some of the most courteous and safe on the roads. When I do call, I'll usually ask to talk to whoever supervises the drivers. I always try to have as many details as possible - time, location, description of both vehicle and driver if possible. And I usually ask, "Should I be calling you, or would it be better to call the police?" They are invariably glad that I'm calling them, and not the police.
It would be NICE if there were a universal "how am I driving" line. Or maybe even a website. When you see somebody driving in a risky or irresponsible way, you could furnish that same info, and easily report the incident. One or two offenses probably wouldn't result in any action... but if the same vehicle is being complained about routinely by other roadway users, perhaps some attention would be merited. (Gallagher - the comedian with the watermelon Sledge-O-Matic - had a similar notion. Motorists should be equipped with guns that fire those suction-cup darts. When you see some really bad driving, you fire a dart that sticks on the offender's car. If a cop sees a car with 10 or 20 darts... that guy is off the road!)
OH - and I'd be totally in favor of a similar program for cyclists! I see as many bike riders - as a percentage of the total - whom I'd just as soon not share roadway space with. That is one of the few reasons I'd entertain the notion of some sort of bicycle licensing program, if it would help to identify the scofflaw cyclists.