Cigarettes and alcohol are highly taxed to discourage their use. The government also spend money on advertising and in the NHS relating to education and treatment.
Do you honestly think that it makes a difference at all to whether people smoke 20 a day and/or drink themselves stupid?
Personally I have no issue with the average speed camera's that are in use now and find them to be a lot more palatable than the Gatso rubbish. It is not necessary to monior every car every second of every day just incase. Reminds me of the ticketing machine in Demolition Man on every corner.