Every vehicle that arrives at it's destination intact is 'preventing accidents'. Self driving or no self driving.Tesla clearly states who is responsible for driving the vehicle. To get into an accident while on AP, you have to be negligent. A simple tap on the brakes disables it.
By the way, there are many examples of Tesla preventing accidents, but they don't get headlines.
Most of us are out there for hours & hours, thousands of miles, preventing. So, no story for committing to common sense.