[legerdemain]

  > This is also why it's easier to talk while waiting for the train,
  > it's a limited time and they feel easier knowing that you won't
  > be potentially annoying them during the whole train ride.

Wait, how does that work? If you're waiting at the same stop, you'll board the same train, right? Unless they wait for the next one to avoid you? Wouldn't they be concerned that you'll board together and continue making conversation for the entire commute?

[TuringTest]

The bus arriving is a natural break point for ending the conversation, I'd say. There's no social obligation to keep talking once you are both are busy boarding the bus and finding a seat, so it's a good time to say farewell.