Say what?
Is that what you call Fed Ex and UPS backing up to the Post Office dock with a semi-truck to UNload? The Post Office delivers to every occupied house that has a box, that isn't on hold, or doesn't have nasty animals. I don't know what color the sky is on your world.
I don't know where you live but in my area the post office has NEVER delivered mail. People have to drive to the post office to get their mail. I could put up 20 mail boxes in front of my house and the post office will still not deliver.
I suggest you do some research because you are showing your ignorance.