Car-Guy
Give me a museum and I'll fill it. (Picasso) Give me a forum ...
When UPS and FedEx come to drop ship their SurePost and SmartPost parcels (respectively) we sign for a manifest that allows UPS/FedEx to quickly scan the manifest and say all the parcels in that manifest have been "transferred to the USPS for delivery" or something like that. At some later point the clerks scan all those packages as "arrival at unit". (Note -- that does NOT yet mean the package is ready for pickup!)
This is where USPS tracking *should* start showing activity -- when USPS scanners acknowledge arrival. Generally, delivery will be attempted no later than the next business day (Monday - Saturday, except for closed businesses on Saturday). Sometimes parcels going to PO boxes will be attempted or delivered the same day.
So, do you know how the USPS charges these carriers for the "last mile" service? Just curious.