The failure modes are going to be very strange and the technology is not strictly comparable to a human driver. It is going to fail in ways that a human never would. Not recognizing obstacles, misrecognizing things, sensors being obscured in a way humans would recognize and fix (you would never drive if you couldn't see out of your eyes!).
It is also possible that if it develops enough it will succeed in ways that a human cannot, such as extremely long monotonous cross-country driving (think 8 hour highway driving) punctuated by a sudden need to intervene within seconds or even milliseconds. Humans are not good at this but technology is. Autonomous cars don't get tired or fatigued. Code doesn't get angry or make otherwise arbitrary and capricious decisions. Autonomous cars can react in milliseconds, whereas humans are much worse.
There will undoubtedly be more accidents if the technology is allowed to develop (and I take no position on this).
It is also possible that if it develops enough it will succeed in ways that a human cannot, such as extremely long monotonous cross-country driving (think 8 hour highway driving) punctuated by a sudden need to intervene within seconds or even milliseconds. Humans are not good at this but technology is. Autonomous cars don't get tired or fatigued. Code doesn't get angry or make otherwise arbitrary and capricious decisions. Autonomous cars can react in milliseconds, whereas humans are much worse.
There will undoubtedly be more accidents if the technology is allowed to develop (and I take no position on this).