It would also likely be prudent to have a human visually inspecting the trucks and able to perform small maintenance tasks. My car can tell me the tire pressure is low, but it can't change the tire. It can tell me the backup sensor is obscured, but it can't clean it. Maybe it didn't even notice it hit something/something hit it (like a fast, low flying bird) and now the fender is hanging off. Things that might need to be done in between distribution centers that would be easier for a human to check, at least in the short term.
Yeah, my guess is we'll see convoys of automated trucks first, with one operator for each line of five or ten trucks. In part for small upkeep and correction in real time, in part to increase the risks of straight up highway robbery... If you can blow out an automated truck's tires and know it will take a day for a repair vehicle to show up, you might as well go for it...
Trucks would be standardized and have sensors to detect many types of damage and the truck could be rerouted to an automated repair facility (or perhaps a repair vehicle would be dispatched). Visual inspection could be done better automatically.
Automation that relies on humans to minimally function is garbage.
There will always be humans overseeing automation for the foreseeable future. At least until we figure out what all will/can go wrong. There are humans supervising automation in factories and warehouses, just in case. It's simply a good idea until we have AI as smart and observant as a human.