There are lots of logistical problems to implementing "automatic" cars, here are a few I just thought of:
- The street departments seem to have a hard enough time trying to keep the streets decent the way they are, I can't imagine them trying to implement equipment to automate vehicles.
- What American wants to spend tax dollars on roads for cars that drive themselves? Driving a car is a right many people wouldn't want to give up lightly, and adding features to our roads so cars can drive themselves reliably is going to be a challenge.
- What happens to the thousands of existing cars? Are they just junk? If you don't require everyone to have an automated car, are the roads any safer? How would automated cars react to non-automated cars?
- To what degree would people be able to drive manually? How would you transition from automatic to manual driving?
Not to say it's impossible, but it probably won't be happening in the near future. If you're going to go to all of this trouble to automatically drive a car, it seems like you might as well have a really good metro train system (with your Segway to travel from stations to destinations and vice versa
)