Recently, I was driving back to the South Bay from San Francisco when I got caught in some stop-and-go traffic, which is a common experience in the Bay Area. I was on the 101, a freeway (motorway in the UK), which is at least six lanes in either direction. When I first came to the US, the widest motorway I had ever seen was the M25, which circles London and which, at that time, had only three lanes in each direction: “the slow lane, the…