I'm not who you're replying too, but I also live in a place with no delivery to the home, despite UPS and FedEx doing so. Everybody in our town gets a free PO Box - I suspect that's how the service obligation is covered. Once a year we have to prove that we still live here to keep the free box.
Their web site seems to suggest they have last mile delivery everywhere because they're under universal service obligation. But, when I lived rural, I remember my mom having to drive to the post office to pick up the mail.
The universal service obligation is not that they have to provide home delivery for everyone, but that they can't close your podunk post office and make life even more hellish for the the 12 households that rely on it that it already is.