many urban buildings have rooftop access. having a landing pad (could be nothing more than a rubber mat with a giant QR code on it) would be workable if the resident can confirm a delivery time to be on the roof. or they could leave the package there, if the building residents use it like a shared mail area.

having said all that this idea of drones flying around all over the place semiautonomously is crazy to me. maybe i'm getting old.