> > even fairly minor violations like failure to pay road tax

> The main use of those cameras is to deter not paying road tax

No-one has paid a road tax in the United Kingdom since 1937. Vehicle excise duty is (currently) based on CO2 emissions (which is why EVs are subject to a £0 VED) and has always gone directly into a general government fund -- it does not maintain the roads. Of course the government could choose to spend some of that money on road upkeep, but they don't have to.