Because if a malfunction happened, it would possibly crash the whole street it's on, because AI probably would not have enough time to react. If that happens, it would take a long time to set everything up and keep the streets clean, since the AI system would probably show many errors.
If self driving cars rely on the gps and the gps is linked with the satellites and if the satellites have a error it will confuse the car causing it to go out of control and crash into a lake, tree, car, house and many more. So that's why it is dangerous
I do believe that self-driving cars could be harmful. While humans can be harmful while driving an automobile we also lack the intelligence and awareness to be careful. We can think quickly and determine if we need to slow down or speed up based on things we see further up the road, where as a self-driving car will not have that much ability.
People are the most dangerous things on the road. If we take ourselves out of the equation, driving would be so much safer. Self-driving cars will stick to the speed limit, leave enough braking room, and will drive much smoother than people. And people with disabilities would be able to go wherever they wanted, when they wanted, without the help of another person.
Self driving cars decrease the amount of accidents and helps the driver rest in long distance trips. Time spent in the car will be free, you can do whatever you want during this time. Also, it is better on the road as it will decrease the amount of crashes and will make it non fatal.
In addition self driven cars leave braking distance which also decrease the amount fatal crashes
Self-driving cars would prevent more accidents and be less harmful to drivers. Computers would drive the speed limit, leave enough braking distance and be alert for other cars on the road. A driver would still be needed to take over in an emergency. However, a self-driving car frees up the driver to do other things such as work.