[orangepurple]

I posit two major reasons.

1. Command and control - Human in the loop is still a necessity because common delivery environments are too complex for an algorithm to navigate successfully so far.

2. Energy - it takes too long to recharge a drone battery pack. Flying is very energy intensive and there just isn't a way to refuel fast enough from the hub for this to make sense yet. The tested, working alternative is to use a two stroke engine but the pollution per mile from those is astronomical.