Autonomous drone delivery requires something analogous to "positive control" used in the existing air traffic control system, yet none of that infrastructure exists. Neither primary nor secondary radar used for aircraft today will work on UASs, so how are they going to be tracked and separation ensured? If it's a decentralized system along the lines of TCAS, that implies some industry agreed upon spec, whether it's active/passive sensing, or whether there's actually communication between UAS's. Any communication probably needs to be cryptographically signed for validation, probably shouldn't be encrypted however so it's transparent. Clearly it has to go beyond existing technologies for aircraft if there will be no role for air traffic control. A whole separate set of expectations and standards for how various kinds of systems failures are to be treated, how does an autonomous UAS determine an emergency, how does it declare one (to reserve a different section of airspace than on its prior "plan" in order to avoid a worse accident), how does it actually perform an emergency landing? Some of these things could be proprietary but other things need to be openly published, namely the spec, the standard, and the metric for performance.

We can't just say "oh, no pilot, rules go out the window" as if everything we've learned about flight safety doesn't apply at all to UASs. No, there's actually a lot of adaptation that needs to be done. A whole lot.