I don't see what is childish about using an example about someone being selfish in a public area and endangering peoples lives and comparing it to smoking. Clearly you don't consider the effects of your 2nd hand smoking to be serious enough, despite the factual evidence suggesting you ought to be. Maybe you are actually that selfish that you don't care?
I'm sorry, are my motor fumes congesting your lungs? Get off the street and in your pub, you have no right to moan about it. Do you see the issue?
Thats my point, I'm not moaning about it as I respect that people like to drive around.