Yes, that's my understanding, too. For quite a while now. That's what got me into the habit of writing snail mail addresses in "machine friendly" format - using USPS "official" abbreviations when I know them, putting the apartment number on the same line as the street name and number, with no comma between the city and stat namese. But the only (rare) times I've ever bothered with Zip+Four have been when I've given my address to someone (usually an government- or corporate-type someone) and wanted to be as sure as humanly possible of getting whatever was being sent to me as quickly as humanly possible...)
Interesting. The "trackable shipments" requirement kinda kills my interest in it, though. With email being the norm for so many commercial transactions these days, I invariably get notice of tracking numbers and just track them myself. (And 99.5% of the packages I get that might require a signature ship via UPS, so delivery instructions are irrelevant.) If it captured "parcels" without tracking numbers, that would be pretty cool, though, since I do get a fair number of those via USPS. But even that's not really a big deal, since I can't recall ever not receiving one that was sent, though it would be nice to have some idea where they were, when.