I feel Amazon,UPS, etc., want as much below 400ft as they can possibly control with cash flow!
I feel it's going to be a long road to profitability for these companies wanting to do full autonomous drone deliveries.
There are SO many factors relating to safety and logistical matters to overcome.
GPS accuracy for this ?
Combined with OA cameras and recent mapping (another big cost) it could work out ok.
True OA, and during landing, MOST important.
Needs Skydio2 type tech, and totally failproof, must see wires, twigs, etc.
Most OA requires good light, so no deliveries after dusk ?
Fast food will be an issue.
Places to land to start is just riddled with problems, driveways perhaps.
Also, you will get numpties trying to interfere with drones during delivery, fast food deliveries and intoxicated or drugged patrons . . . or small children getting too close in excitement etc.
The talk is that for introductions, they will need a pilot in a control room to monitor a flight.
I suppose driver and vehicle cost could be higher, but then they deliver perhaps many dozens or more individual locations during a daily run.
Companies will need fairly nearby, and well stocked warehouses to ship from, or goods will need to go by truck (see point above) and fairly often for fast moving items.
I have seen the medical zipline type craft are very good at what they do, but there are qualified and trained people at either end of the process.
I'm not convinced the masses are ready to be part of that type of system with food / products / mail, whatever.
Professional industry type deliveries are proven to be one way autonomous deliveries can work, but for what is being proposed, they are probably never going to be able to overcome potential human stupidity at the delivery end.