It looks like the Tesla driver will be at least as fault for the collision with the car behind it. However, it seems the subsequent collisions were caused by fleshy human drivers driving unsafely. I don't know much about traffic law, so I'm unsure how responsibility for the overall pileup will be divided.

From the police report:

> V-1 made an unsafe lane change (21658(a) California Vehicle Code) and was slowing to a stop directly into V-2's path of travel. This caused the front of V-2 to collide into the rear of V-1 (4.0.1. #1). P-2 did not have enough time to perceive and react to V-1's lane change.

V-1 = The Tesla

> P-4 observed V-3 stopping and applied V-4's brakes. V-3 came to a stop to the rear of V-2. P-5 observed V-4 stopping and applied V-5's brakes. As V4 slowed down, P-4 steered V4 towards the #2 lane. Due to P-5's unsafe speed for stopped traffic ahead (22350 California Vehicle Code), P-S failed to safely stop behind V-4 and V-3. The front of V-5 collided into the rear of V-4 (A.O.L #2). V-4 moved into the #2 lane without colliding into any other vehicles. V-5 came to a stop in the #1 lane after colliding into the rear of V-3 (A.O.L #3).

and it goes on from there...

https://www.documentcloud.org/documents/23569059-9335-2022-0...