The perception of danger in planes and self-driving cars is perceived as such due to lack of control. If a plane is about to crash, there's not much to do besides hold and pray. If your car accelerates when it's supposed to brake, you better be paying attention and act fast to avoid a crash. With your hands on the wheel, you're always in a position to act, and it's easier to believe that there's always something you can do to avoid disaster.