I figure he got comfortable like a lot of other normal drivers do, maybe it’s my paranoia but I think many drivers would have reacted poorly in his situation. A lot of people drive in predictable places and then they go traveling and they merge at 50 km/h directly in front of a semi going closer to 90 km/h while I sit on the on ramp thinking but I’m the one who hit my head, why are you like this ? Back in drivers ed my instructor randomly said “ I see a cop car, do you” and then went on a story about how he never got a ticket because he was always scanning. His main point was that a lot of people get comfortable and stop scanning and looking for the seemingly unpredictable. I do agree that the likelihood of the human safety driver being aware enough to intervene is low because they aren’t really engaged in the driving process before that point. They really seem like more of a false sense of security.