Once upon a time, the mailman walked from house to house and put the mail through a slot in the door, or in a box attached to the house. Still does in some places, I guess. In more rural areas, the mailbox is always out at the end of the driveway on a post, so the mailman can deliver with a car.
So, can someone who lives in a rural area just put a box on their house and expect the mailman to deliver to it? I assume not, but what’s the difference?