I suspect what Jmstuckman meant was that the controls were not intuitive to humans, or have a range of control that is awkward. In other words, imagine that the gas pedal on your car had 1 mm of travel
I have driven trains. They have massive momentum, but feeble acceleration and braking. Make a normal brake application at full speed and nothing seems to happen for a while. Driving them is quite a knack, nothing like driving a car, and you need to be familiar with what is still out of sight ahead. I think that a human taking over from auto will do poorly because, as the train is in usually auto, they are simply out of practice.
Incidentally, the train (electric ones at least that I have driven) might as well have only 1mm of control handle travel. You drive them full on or off. For a lower speed you tend to nudge it along.