No, you are quite right, jake. Of course there are degrees of seriousness and my comparison was not perhaps very well chosen. However, I do not see tax evasion as a “victimless” crime because to a greater or lesser degree we are all victims of it.
The issue I have is that helping the authorities in such a matter is somehow seen as “dirty” work. Of course people should be free to help or not as they wish. But those who choose to help should not be accused of somehow undertaking “dirty work”.
Your idea of an insurance disc, Dodger, is a good one. It has been suggested in the past but rejected because of the complications caused by the fact that drivers are often insured to drive cars other than their own, so they may be insured to drive a vehicle although that vehicle may not be specifically insured in its own right. However, with the Road Safety Act 2006 comes a provision that all vehicles kept on the road must be continuously insured, so that objection is largely overcome.