Whether it performed as designed or not really isn't relevant. The salient point here is Tesla's promotion of an "auto-pilot" system that encourages users to take their attention off of the road and put too much faith in a glorified lane-following system.
Now, this is pure speculation, but I really can't imagine running into the side of an 18-wheeler crossing the highway unless A) I was traveling at a reckless speed (unlikely given that "auto-pilot" was on) or B) I wasn't paying attention to the road.
Now, this is pure speculation, but I really can't imagine running into the side of an 18-wheeler crossing the highway unless A) I was traveling at a reckless speed (unlikely given that "auto-pilot" was on) or B) I wasn't paying attention to the road.