I no longer have that problem but let me give an example. Person lives in a small condo complex that does not provide a cluster box (CBU) for mail delivery by USPS. Residents then must get a PO Box for delivery or, if they are short term seasonal in a rural area, they may be able to get the post office to hold mail at the counter for them to pick up periodically (they aren't thrilled to do this either).
I'm way off any public road and there's nowhere to put a mailbox. I could get a PO Box at the local post office, but why should I pay for that when I can get my mail delivered to my office location?
There's pros and cons to every living situation. The frustration you're experiencing is entirely of your own creation. I'm glad the post office has not spent time optimizing their program on the edgiest of edge cases here, like your housing decision to live in a house with no mailbox. Maybe they eventually get around to it, but in no way should they have waited to roll this out to address your use case.