It seems like it was during the day as well. My guess is he was looking down at his phone and not up at the road.
Get a windscreen mount for your cellphone so you can quickly switch between checking the GPS and the road.
Whenever I use directions, I look over the whole route first so I have a fair idea of what the turns are going to be etc before I even put the car in gear. Then you’re kind of expecting what to happen rather than being surprised when a turn comes up.