I have been noticing a substantial increase over the last few years in motorbikes missing license plates, most commonly on the freeway, and often riding with zero respect for other riders or the speed limit and other road rules. I am aware of the existence of license plate "flippers" that many use to hide/show the plate at will…
… what do you think could/should be done? No wrong answers.
Given the way these people ride, it's only a temporary problem.