I'm not necessarily arguing for this, but one viewpoint might be: A vehicle that can autodrive the freeway (i.e. most of the way), and reverts to manual control for the shorter sections before and after the freeway, would have a significant convenience benefit over a train.

Take the train, and you have no vehicle with which to go from the destination station to your endpoint. Also, you could travel at any time instead of being held to the schedule.