Only about 1 in every 1,000 cycling accidents and offences are reported and that is when there is a serious injury.
I can't imagine the majority of driver offences are reported. People forever run red lights, stop over pedestrian crossings and use their phones while driving but aren't reported.
I'd be anti compulsory insurance as it's just a barrier to the casual cyclist. One of the good things about it is that you can just go.