Specialized in flying, including eyes and brains, at that!
Autopiloted is much easier than cars because air space is less crowded with less obstacles and extremely well controlled. Low flying delivery drones don't fall in that bucket.
Less crowded now. But if they take over all those deliveries that are going on now the sky will get quite crowded and I suspect we will see people asking for no fly zones and for drones to be constrained to fly along roads instead of low over people's gardens. I certainly don't want hundreds of drones flying over my garden every day. Something like 35 million people in the UK buy something online every week, that would be a lot of drones. If you imagine that there is a distribution centre for every 50 000 people in the UK, that's roughly 1 500 distribution centres each with over 3 000 drone flights per day.
I realize that this is a very rough calculation and that of course there would be large variations in flight frequency but no one else seems to be showing anything better.
With thousands of drones crossing the city sky, there would have to be some kind of system to organize that traffic, both to minimize collisions and sound pollution.
It's not hard to imagine how systems like that could be organized.
It's also important to consider how many road vehicle trips this would replace.
Only on places where they concentrate. It's not really flying that is difficult, it's approach and take-off, because they have to go through all of the heights.
Anyway, I guess the main problem is that most people will not want a sky full of drones just so that some random Joes can get their stuff from Amazon or AliExpress a little sooner.
If the skies fill with drones while traffic jams ease, there’s less double parking for delivery, and streets generally start looking more airy, people may make the association.