Thinking about this in the context of a real-life scenario, in my case the three or four times a year trip down to the west country, I have many times, waiting in line to get past Stonehenge, wondered why we are all doing 2MPH rather than 30MPH.
There's a pinch point, a one-lane stretch of road through which cars go in single file at a crawl. Beyond that point, the open road, with cars immediately able to return to 50MPH or whatever. Given that the road beyond the pinchpoint is completely clear, why don't/can't all cars go through it at, say, 30MPH? The only answer I can think of is inefficient merging, which builds on itself, reinforcing the delays, and ending up with the net result: a crawling pinch point, with a big reservoir of cars backed up behind it, and a trickle coming out the other end.
I wonder if one day, when Google's driverless cars have become universal, with cars not only driving themselves independently with maximum efficiency, but communicating wirelessly in real time so that the entire 'car universe' works cooperatively to maximise efficiency, such pinch points would if not disappear (there's always going to be potential for a fundamental mismatch between the demand for any given road capacity and the amount of road capacity available) at least have their negative effects minimised, by cars merging flawlessly, like teeth in a zipper.
(Sits back and waits for somebody who understands maths/mechanics to explain a) how wrong he is, and b) how stupid he is not to see it, using logic and language he will c) fortunately be too dumb to grasp.)
