Many pepole are the innocent victims of drivers on the road without the necessary insurance cover and presumably feel no need to do so while they can get away with it. This is plainly wrong and unfair. They have also chosen not to pay the appriopriate tax for the privilege of driving, which again is unfair.
Would it not be a valuable consideration that traffic wardens should be obliged to check vehicle tax discs. Individuals have already broken the law by not having one. More seriously, they are likely not to have any car insurance either.