From what I learned, saw and experienced, when you want to replace man by a robot, you should not try to copy existing actions and replace them by an automated system. You should think the process again and adapt it to the machine.
So if you want an automatic loading of a trailer, of a container, the loaded device should be adapted in order to allow an easy access and a high stability during transport.
When French engineers created an automated underground train, they placed a wall with doors on the underground dock and the train had to stop so that train's doors and dock's door would be on the same place (just like in an elevator).
Same thing, if you want a full automatic loading of trailers, you'll have to adapt the loading and the loaded device. This could mean compatibility issues when going from one factory to another. This is why I believe that the interface functions will be the last ones to be automatic. On regular lines, it's quite easy to manage, but for all the punctual trips, this could be a major issue.