This idea would help to bring safety to our roads where it is much needed and help the law-abiding majority to stay within the speed limits safely. Tailgating is not only extremely dangerous; it also causes aggressive driving which can make the traffic more dangerous especially for other road users such as cyclists.
The people who do these things often go undetected and people can often not remember (or didn't see) the number plate when they're the victim of a tailgater.
I remember being tailgated myself through a 20mph speed limit zone and about 100 yards before the (fixed) speed camera, the offender turned off and disappeared. Even if I had some how taken down his number plate details, I still wouldn't have had any evidence to show what he did behind me – tailgating, he swerved wildly behind me several times and I could see him fuming in my rear-view mirror and making threatening gestures. There was I obeying the speed limit, and this guy (who obviously knew the roads) was dangerously trying to force me to speed up so that I would get caught on the speed camera.
This kind of behaviour needs better policing and I think my idea is one way that could perhaps be trialled.