Sounds like it would result in less accountability and efficiency, and an arbitrary line to draw.
You doubt that which is easily verified?
> don’t pay another business for dealing with the inventory
What do you think UPS and FedEx does? Shipping is not instantaneous and most of it is logistics. Warehouses are often rented. Amazon produces very few physical products and most are on consignment anyways. What model are you imaginging?
> Sounds like it would result in less accountability and efficiency
To have multiple businesses competing for these deliveries? I'm not sure how you arrive at that conclusion.
> and an arbitrary line to draw.
As stated, they _used_ to do this, it's not at all arbitrary.
Amazon does not deliver to customers. They pay separate businesses (they call them delivery service partners) to deliver to customers:
https://hiring.amazon.com/job-opportunities/delivery-driver-...
FedEx does the same thing with FedEx Ground: