If something goes wrong, as we've seen with Tesla, the car tends to barrel full-speed into very solid obstacles. Because, duh, something went wrong. Human err

If something goes wrong, as we've seen with Tesla, the car tends to barrel full-speed into very solid obstacles. Because, duh, something went wrong. Human errors tend to be misjudging something and then getting into a situation that, due to physics, they can't quite get out of. So you can't quite stop the car in time and you hit the car in front of you at 15mph. Car errors are going to be things like "I thought the tractor trailer was a billboard or a bird so I hit it at 60mph with no braking". Or "I lost all sensor data and got stuck in a loop so I drove off the bridge". It's a fundamentally different sort of error.