You raise an interesting point about energy per delivery. In you example, which one is lower per package? I assume the electric truck.

Considering the distance from one delivery to the next in a van is short, and the warehouse to town distance is split via a hundred packages, it just has to be the electric van. Maybe things will make more sense if the drone can carry 20 lightweight packages. But even then you gotta wonder how much energy it takes to hover/fight gravity the entirety of the trip.