Drone delivery would be Painfully slow. Take a package -Fly back on and on
I think the concept was more rural, out of the way locations could be done from the nest van, simply to save a long round trip to some backcountry home.
It could work like that, if other parcels were delivered while that was happening, regular van stops, guy throws package over fence, or onto porch from 20' away (lol), while the drone does some trip off yonder to save that drive time.
The drone could return to whatever location the driver / van was after it had done its delivery.
Lots of pros cons to work through of course, probably what these trials held in the US and certain Australian locations was all about.
For now, a van and driver could leave base with maybe 100 packages to deliver on a computer programmed run for efficiency (I don't know exactly how many they do, how much pressure i on those drivers) . . . not sure a drone from a location to X miles out could compete with that in the near future, perhaps a decade away ?
There needs to be the initial trials, errors, calculations, revision of systems etc, takes time.