Multiple independent sensor streams is like having multiple pilots fly a plane instead of just one pilot. The chance of a fatal error (false negative identification of an object near the car) decreases from p to p^n. The size of that decrease is not intuitive: if p=0.0001 it now becomes a much smaller number with the introduction of a second pilot or second independent sensor stream (0.0001^2).
Now the errors are not all independent so it's not as good as that, but many classes of errors are independent (e.g. two pilots getting a heart attack versus just one) so you can get pretty close to that p^n. Musk did not understand this. He's just not as smart as he's made out to be.
Now the errors are not all independent so it's not as good as that, but many classes of errors are independent (e.g. two pilots getting a heart attack versus just one) so you can get pretty close to that p^n. Musk did not understand this. He's just not as smart as he's made out to be.