Most of the time when a human does it is because they were either operating the car while they were tired or ill which interfered with their ability to pay atte

Most of the time when a human does it is because they were either operating the car while they were tired or ill which interfered with their ability to pay attention or they were doing human stuff that distracted them such as dealing with kids, talking to others in the car or by phone, daydreaming, looking at something interesting on the side of the road, panicking because they just noticed a big spider on the ceiling above them, and so on. A self-driving car should not get tired. It shouldn't be doing any robotic equivalent of those things that distract humans. This is why almost hitting things is a bigger deal for self-driving cars. Humans are expected to almost hit things, because we do a lot more than drive cars and we are easily distracted. A self-driving car is a specialized system designed for that one task. If it almost hits something it is either a sign that there is a flaw in how the system works, the real world testing was not good enough, or it has hit an extremely rare edge case