Probably not relevant. Amazon uses dirt cheap subcontractors for delivery in cities and suburbs. Then they let the Post Office deliver out in the sticks where nobody can make money.
Sam’s question seems to be how much would the boondocks rates have to go up to attract other providers.
UPS has a service called My Choice Premium for $15/year. It allows for upgrades of UPS SurePost "last mile" packages from the post office to my house so that UPS delivers it the whole way. Saves a day on the delivery time. Plus allows the package to be delivered on another day, etc.
Wish FedEx had a similar service, but doesn't look like they do.