Ok, show me the owl silently towing a few cases of beer and I'll take that into account ;)

Edit: OK, on reread this is far more snarky than is deserved. Sorry!

I get what you're saying about the noise per unit weight! Clearly nature has potential ways to improve on the technology, though I have to wonder how much development is necessary until a drone could restock my corner store at the same noise level as a van does.

Overall, my larger concern, which should have been listed first, is that delivery traffic is not the primary cause of traffic on our roads. Eliminating it won't solve our transit issues in cities.