What you are saying may be true as far as deliveries. But what happens before that? I take it you have no idea how the mail really flows to the delivery unit, nor have you ever worked at a Processing Center. Might want to read this http://www.usps.com/communications/news/press/2006/pr06_048.htm. Basicly what it comes down to is Fed Ex moves any and all USPS mail that needs to flown, which if I remember right is about 80% of the USPS mail volume. Years ago the Post Office had facilities nationwide at Major airports. The mail was loaded on commercial aircraft for transport across country. But, and I may be wrong, all of them have been closed. In Phoenix all mail that was not to be transported by ground, which was basicly anything beyond 500 miles or so went to the West Valley Facility. There is was loaded into Fed Ex containers for Fed Ex to fly it. It used to be that Fed Ex only moved time sensitive mail for the Post Office. Bulk rate/parcel post were ground transported by the Post Office and its Highway Contract route transportation network. But now Fed Ex moves it all.