"but I do think drone-based delivery will be rejected by consumers if it ever reaches significant scale in non-rural areas"
I'd wager it's the opposite: Rural areas would notice the one off noise of a drone flying overhead because humans notice novel sounds more. In an urban area you already have other significant sources of noise (traffic mainly) and if the drones are ubiquitous it might just be more of a background constant that people tune out.
I'd wager it's the opposite: Rural areas would notice the one off noise of a drone flying overhead because humans notice novel sounds more. In an urban area you already have other significant sources of noise (traffic mainly) and if the drones are ubiquitous it might just be more of a background constant that people tune out.