Drive-thru places are popular because Americans have become accustomed to convenience and, generally, don't care about their health. I've witnessed people drive in circles at parking lots waiting for a parking spot a mere 20 feet closer to the door to open up. It's no wonder why America is the fattest and unhealthiest country in the world.
And, yes, fast food places cause pollution and obesity, plus they have destroyed our food. We must boycott them and choose organic to affect change!
Here's a related hub I wrote on this. The movie, Food, Inc. discusses the negative impact that McDonalds has on our food sources.