Originally Posted by mconlonx

Because the listener perceives you as saying "You are certainly a carbon polluter and also pollute the environment in other ways. Get rid of a necessary part of your life (car) in order to be as environmentally holier-than-thou as me." ...even if they claim otherwise to be environmentally aware and active.

You are attacking them and their cherished beliefs -- regardless of the bottom line situational reality -- why do you think you would not get backlash/criticism? Such responses seem to be just a part of general human nature, not limited to this particular debate.

Were I to argue car-free advocacy, I'd much more stress the immediate positive aspects of being car-free, rather than pointing accusatory -- or even the perception of being accusatory -- fingers at car drivers as polluters, or any environmental aspect.

It's akin to arguing about vegetarianism -- when political/ethical vegetarians delve into saving the world and animals, my eyes roll; when I advocate vegetarianism, it's from a strictly self-interest POV. Health aspects, mainly, but also good and regular pooping, smelling better in general, lower cost at the grocery store, etc.