Sam’s question seems to be how much would the boondocks rates have to go up to attract other providers.
Right now you type in a zip and get a shipping rate that's more or less the same everywhere. At some point they will refine it to an address and calculate that the truck will have to drive 5 extra miles to drop just that one package. They'll have to raise the rates a couple bucks just for fuel, plus more for the driver's time.