We live in a WalMart society. Businesses race to get costs and wages as low as they can be and provide the lowest exceptable level of customer service. No company can provide a high corporate dividend and provide a high level of expensive customer service. The math does not work.
If you shop at Walmart or go to a brick and mortar shop to look at something and then buy it online for less, you are part of the problem.
"Part of the problem?"
I think it's more consumer demand, and convenience, that is the issue at play here; as a company, we sell service, not ideals.
The obvious retort is that if there is a consignee physically close to the post office, and their parcel is shipped via SurePost, then (if we sell service, as I've intimated) why not deliver it? That is above my pay grade, unfortunately; however, I suspect the answer has something to do with "because that is what the contract says." Making service on the odd SurePost package that you feel is "close enough" might, when extrapolated across the country, cost millions of dollars per quarter.
On a topic related to the OP's post, consider the SurePost missorts that occur daily; almost every day, the center where I am employed gets a call from one of the PO's we provide service to wondering why they got a package for an area they don't service; now, they have to either send it back to us and we send it to the right PO, or get it there themselves.
Also, what a lot of centers that are heavy in SurePost do now is link all the packages to a single (or two, maybe three) ULD tag(s), so that the driver only has to scan the ULD tag(s) in question; there is no scanning bags, no scanning the "loose" packages; just scan the tags, and then snowblow the SurePost off the truck into the mail cart(s). The upshot is that this saves the driver time on that stop; the downside is that the dispatch piles on more stops because they know the PO (that used to be a 1.5 hour stop) became a quicker stop. If you have not seen this yet, keep an eye out for it soon - the IE/OE folks insist it should not be done this way, but the Operations managers like it - as far as I can tell, anyway.
Some operations even give the preloader a scanner set for USPS, and have them scan/bag it all on the belts; this slows them down and puts more pressure on the soups, but frees up small sort to take volume that might otherwise be held back.
As I see it, anyway.