Many decisions that a government takes have unwanted side effects. For example, while everyone surely thinks it's a good idea to stop people smoking, the government takes £6.50 plus 16.5% of the retail price from every packet of cigarettes: tobacco duties raise about £8.8 billion a year at the moment. The response is often 'yes, but if we can get people off cigarettes it would reduce costs to the NHS'. It would - but only by an estimated £2.6 billion. So the exchequer would still be £6.2 billion a year worse off if we got everyone to stop. There is a similar issue with electric cars. At the moment, the fuel duty on petrol (gasoline) and diesel in the UK raises an eyewatering £28 billion annually. If we could wave a magic wand and switch everyone overnight to electric vehicles, that income would currently disappear. And though drivers might cheer, the government would certainly not be happy. So for some time there have been schemes afoot to recoup these potential losses. I ...