It’s not unavoidable. But it’s a black car stopped without lights in the middle of a freeway at night. It’s just a matter of time if no one intervenes (e.g. cops with flashing lights drawing attention).

Ehh. I think it's actually 100% avoidable with a robust self driving solution. One with a smart enough margin of safety would never be in a situation where it has so little information that it initiates a crash on the highway

That's not a given. From the report:

"According to the NTSB, a witness had come across the stopped CR-V prior to the collision and noted that neither its taillights or hazard lights were illuminated, She was able to change lanes and avoid hitting the Honda, but after she passed it, she saw the Mach-E strike the stopped crossover in her rearview mirror."

That means the witness car likely obstructed the view of the stopped vehicle, then changed lanes at the last minute, revealing the stopped vehicle after it was too late for the Ford to stop.