Just a thought:
How many of us, hand on heart, would take advantage of our size and performance and occasionally behave in much the same way as some cyclists if we did not have registration plates?
In other words, is our behaviour determined by our high moral standards, or is it determined by the repercussions of being caught and punished?
Just think, without a means to identify us, we could use any bus lane with impunity, pass keep left signs on the right, go through red lights, go up one way streets the wrong way, and ride on the pavement when it suits us.
So, think about it. Would you really, really keep on obeying the law? In every situation? Late for work, late for an appointment, late for a date? Are we motorcyclists the little angels that we seem to think we are?
The fact is that we don't do any of these things because we can be identified and punished if caught.
The fact that cyclists can do all of these things and not get caught and punished is the problem.