They may explain the US, although I doubt it. It doesn't explain literally every single other industrialized nation in the world, including the many ones without a powerful auto industry.
> They have predictable and easily controllable failure modes
So will drones, once they mature. And despite all the predictability and controllability, trucks still fall over or get themselves wedged under bridges etc, shutting down traffic for hours.
> they're always traveling at eye level where they're relatively (easier) to spot
Except when they're around a corner, and it's not much help to a cyclist about to be crushed by a turning truck.
> they have relatively high transport capacity
For drones to be competitive they will have to be competitive with this fact. If you're right, drones will never take off (pun intended). If you're wrong, you're wrong.
So yes, I think sans massive government corruption, we don't see these kinds of technologies that are intrusive and inefficient rising to prominence.
Also, trucks hit a technological sweet spot that I don't think drones sit in. They have predictable and easily controllable failure modes; they're always traveling at eye level where they're relatively (easier) to spot; they have relatively high transport capacity, enabling multiple visits; etc.
The problem with drones that replace trucks is that I'm not sure we've actually gained much by having flying trucks all over the place - the increase in delivery time (which I'm not sure would actually be very high in the average case) would easily be offset by the danger of many low flying trucks.