Those two are parcel and document transfer points in the main - Not much tonnage on the those Fed Ex/UPS planes in reality.
Try either with a pallet of machinery and a manufacturing exporter would likely never win any orders.
That said global electronic companies such as Apple use them to deliver from Foxcomm factories direct to customers because it allows them to have virtually no inventory sitting on their shelves !
The likes of Foxcomm take that risk !