> Even then, it's not really clear why UPS or DHL or whomever would trust a random person in their car vs. their sophisticated logistics networks.

Amazon seems to have a sophisticated logistics network that is built at least 50% on random people in their car in Southern California. What I don't get is why someone with an existing logistics network of any kind would rely on a third party to integrate the random person rather than doing it in-house.

Liability. I.e. when they get sued they can try to argue the contractor is an employee of the nothing firm and doesn't need an equivalent retirement plan to Bezos.