While a lot of people seem to be focused on the car, I’m much more focused on how the big rig driver missed that there was oncoming traffic before he pulled across lanes.
This type of accident isn’t exactly super uncommon - parts of Europe require barriers under trucks to prevent such accidents.
As for the radar sensor, I think the biggest issue is that most times such systems focus quite low (so they can detect incidents in front of the car ahead.) I doubt that it would detect a big rig trailer across the lane of traffic. If the trailer was a little ahead or behind where it was, this accident probably wouldn’t have happened.
Left turn in front of oncoming is the leading killer of motorcyclists IIRC. (for 2 vehicle accidents, too hot into a curve for solo)
Speed may have been a factor. I read elsewhere that the car came to a stop a quarter mile down the road.