> This is 100% the drivers fault though, it is extremely easy to override Autopilot
That's speculation. Do we know if the car had suddenly lost the ability to continue driving? Was the car pulling to the closest side of the road? If you lose power in a gas powered vehicle, have a flat, or some other failure when you're in the far left lane, what should be done?
From the video, it looks like a lot of people are following way too closely. Far less than the 3-second rule would allow for.
The first vehicle behind that crashed got caught by the sudden lane change.
The second vehicle avoided rear ending them. You can see the weight and suspension settle just before it gets hit from behind.
Three was slowing and trying to avoid the crash (it shifts lanes and makes it past), while the fourth was in a rush to get past three (you can barely see it, that's how close they were following).
While the quick pull to the left side of the road probably initiated things and caused the first vehicle to rear end the Tesla, the pile up is the fault of the fourth car (which can barely be seen behind the pickup that managed to avoid it), and all the others that were clearly following way too closely.