Notice in Bombay railway station: The times shown on these timetables are not the times at which the trains will depart. They are the times before which the trains will not depart
Actually, we have the same system with our buses. Certain stops are designated timed stops. If the bus arrives there a little early, it must wait until the designated time
You can understand why. It is frustrating if the bus is late, but imagine how infuriating if you are walking to the stop with a minute or two to spare, only to see your bus drive off into the distance
It says much for the general reliability of our service, despite the very best efforts of the gas board & other utilities, that such a system can be in place
Of course not every passenger is aware of this. They get cross; they are in a hurry. Some even feel compelled to share, loudly, with other passengers, their opinion of the lazy, idle, so-and-so of a driver