Plus, trains (and cars and planes and buses and taxis and limos and horse buggies and ... and ...) are generally under the control of an entity with a sense of

Plus, trains (and cars and planes and buses and taxis and limos and horse buggies and ... and ...) are generally under the control of an entity with a sense of self-preservation, and actually cares about getting home tonight. Contrasted with an auto-auto, which will cheerfully drive into a wall when you least expect it.