When I first rode a train to school in what is the equivalent of middle school in the US, many of the trains had manual doors. Passengers could open and close the doors as they wished. It was common for kids to ride with the doors wide open – for the fun, thrill, and cool factor. I was one of them. Often the trains/doors were so old that one of them would open from inertia every time the train started/stopped anyway. These were trains that were built in 1926-1960 according to wikipedia.
Anyway. That’s just an anecdote. It’s 2012 now… metro is teh suck.