One way drones would be step backwards. One way would create a different set of practical problems in managing a fleet. The solution is having a combination of

One way drones would be step backwards. One way would create a different set of practical problems in managing a fleet. The solution is having a combination of an aircraft carrier and mid-air refueling. Vans full of packages to be delivered are the aircraft carrier and vans that are empty or low on packages represent the mid-air refuel because they can swap out the battery/fuel. Drones don't have to return to same van, but the closest, or whatever optimization you are looking for. Minimize the movement and energy required for heavier, more energy intensive components (the aircraft carrier) while making the most of the drones capabilities.