One of the most surreal moments I had, where I wished I had a dash cam, was driving to work on the M40 one Saturday morning.
Overtaking a car in lane 1, me in lane 2. Carriageway was coming off a crest, and about 500 yards in front, was another car, nose into armco in central reservation. Thinking that's not good, start apply brakes at (cough) 70mph. When suddenly, out pops from behind car in armco, another car, but heading in my direction in lane 2. That is, heading north on the southbound. I see the whites of his eyes, when I'm about to go into lane 3, when he does and drives straight by
Old chap, got confused at motorway junction, and joined the M40 via the off ramp. Ten collisions, and 20 miles later, he spun round and joined the normal traffic flow, and was pulled over. Luckily, no one was badly hurt. Might have been different story, on a weekday morning, with heavy traffic.
What cheeses me off with most of those incidents, is the drivers with the dash cams, can see the collision going to happen in front of them, but still continue on until the crunch.