I think the key thing people need to realize from the SAE definition [1] of the levels is that they represent designs of the system rather than abilities of the system. I could slap a camera on my dashboard, tell the car to go when it sees green pixels in the top half of its field of view and stop when it sees red pixels. Then I could get out the car and turn it on, and for the 5 seconds it took for that car to kill a pedestrian and crash into a tree, that would be level 5 self driving.

So when people talk about a particular company "achieving" level 4 or level 5, I don't know what they mean. Maybe they mean achieving it "safely" which is murky, since any system can crash. Maybe they mean achieving it legally on public roads, in which case, it's a legal achievement (although depending on what regulatory hoops they had to go through, maybe they had to make technical achievements as well).

[1] : https://web.archive.org/web/20161120142825/http://www.sae.or...