The Dirty Tesla YouTube channel gives a pretty convincing explanation for that.
When I wrote “The Four Sides Of A Tesla Autopilot Crash Are Revealed By NTSB,” I did not know that Tesla says Autopilot may not work in some situations. One of them is precisely the one that happened in that accident. Thanks to this Dirty Tesla YouTube channel video, I am now aware of that. So this article joins Dirty Tesla’s effort to make this clear: Autopilot will probably not stop for service vehicles parked in lanes of traffic.
Gallery: Why Autopilot Doesn’t Avoid Crashes With Service Vehicles? Learn With This Video