[elithrar]

> We have had driverless trains for decades

Yet we are only still trialling driverless trucks on mine sites. Even with the sites modelled entirely (and frequently), and with LiDAR, radar and cameras on the trucks, it is still far from perfect. I would argue that an aircraft is in an even less controlled environment (you can stop the trucks when it all goes wrong or comms fails!), which is why it's such a hard problem.

Trains, relative to trucks and planes, are literally on rails. This removes one of the greatest challenges (navigation).