Bullshit. Mirrors don't show jack. The only way to know what is around you is to actually turn your head and look. You want to move to the left, turn your head and look. You want to move to the right, turn your head to the right. If you want to know what's behind you, turn your body and look behind you.There is no excuse for the cager to not have used his rear view mirror.
A rear view mirror shows you what is BEHIND you, not what is next to you. Side view mirrors (I was driving before cars had TWO) show you some of what is on the side of your car, not everything. If you want to know everything, turn your head and look. And even then, as your story says, you sometimes miss someone, but hopefully not.