There are now electric cars, and there have been bicycles and buses for a long time. Most people choose polluting cars because they are cheaper and more convenient. For most people, choosing a different means of transportation wouldn't cost anybody else their job, or put our means of income at great risk. Before condemning the actions of others, try to ask yourself what it would take to get you to stop doing a similar thing. Federal laws usually do it, but not always.
Attitudes are a hard thing to change.
It isn't as if gas-fueled cars were our only option.