What if something happens to the lead driver of a road-train? Would everyone connected be screwed? It is scary to rely on a complete stranger to not fall asleep or have a heart attack or swerve to avoid a deer or spill hot coffee on his/her lap. Would that put everyone in the train in danger? With a real train there are tracks and a crew of more than one to handle an emergency. If you have 6 cars following each other and mimicking the first car’s moves, there could be a 6 car crash.
Is that what guide rails would be for?