Plenty of motorists get fined everyday.
Just because number plates aren't used elsewhere, doesn't mean they shouldn't be used here.
I'm not surprised some drivers' patience with inconsiderate cyclists is exhausted - the tailbacks caused by a single cyclist who doesn't use the perfectly adequate cycle path alongside*, constructed at no little expense, because he doesn't have to, and has the right to ride on the road.
[*A15 everyday]
Sorry but IMO, cyclists should be insured, and registered like every other road user must be - and forced to use cycle paths where provided.
If you want to introduce something that no other country has got and many countries have abandoned.... Your choice but do you really think that the advantages are worth the considerable disadvantages? The same issues apply to registering and insuring cyclists. Many regular cyclists are insured but you don't hear about that... You do hear about the yobs that cycle recklessly and damage other vehicles and people and then cycle off.... A bit like yobs in cars who do hit and runs... Do they get caught often?
I don't knowing about the A15 cycle path but many are not fit for purpose.