I think it has more to do with American culture in general. Most people are lazy. This is why automatics are so popular. Only 6% of all cars on the road in the USA have manual transmissions.
Another thing is that most people don't consider cars to be complicated, but rather an appliance to get you from point a to point b. I've met people who have no idea of the concept of car maintenance and think the only thing you have to do for a car is put gas in and go. I personally firmly believe that if you have no interest in cars, you shouldn't be driving. If you have no interest in something, generally, you can't do it well. You wouldn't ask me to rebuild a computer.