It always puzzpes me that people with zero idea how dirt cheap shipping is per unit believe drones, or moving production closer to consumers, woupd ever work from a price/cost point of view... And since the last mile is the most difficult one, supermarkets are pretty good in outspurcing that to customers.
For now. Who is going to be the first company to pull it off though? I'd definitely subscribe to that - would love fresh produce parcels dropped off on my front steps or backyard by drone delivery. This has already been done with medical supplies before which is super cool.
I really don't think it's feasible without some kind of AGI (or human) on the controls. There are so many environmental, technical, societal and regulatory issues to tackle. They make a lot of noise (although some are much quieter now), people could very easily jam their communication signals (or just shoot at them), birds, hardware failures, ... I worked on last-mile delivery project at a drone startup, we could do cool demos that impressed shareholders, but I could never see that working in the wild, people would get hurt.
Also, once you solve the last-mile problem, a new one arises: the last-foot problem...