It's not just the USPS, while the USPS entered into a sweet heart deal for the Chinese and amazon. The cost of overnight shipping and 2nd shipping has gone way up for the individual. I'm guessing FedEx and UPS cut sweet heart deals with the big overnight shippers. Now the individual essentially pays a tax every time they have to ship something overnight just so FedEx/UPS can offer a discount to he Amazons of the world
I think it's more likely that with USPS raising it's rates to individual US customers, FedEx and UPS simply followed suit, since they no longer had to compete with USPS as vigorously. (That is not to say that doing so did not allow UPS and FedEx to make big shippers a better deal -- but one does not have to be anywhere near the size of Amazon to get substantial discounts, and that was true even several (10 or more?) years ago. I can speak with experience to that.)
Also, it seems to me that the program FedEx had going with contracted local delivery people went away due to some sort of legal problem with it, IIRC. Back then, that method of shipment & delivery by FedEx was usually the cheapest option...