This. Within weeks of Trump complaining about how much the USPS charges Amazon, the amount of Amazon packages being delivered by USPS in my area trickled to nothing, before then they were delivering the bulk of them., including all the Sunday ones. Now it's almost always Amazon contractors.
Amazon has been building their own urban shipping service for some while, an in house version of UPS or Fedex. The latter have a whole series of agreements with USPS about air/ground shipping & last leg delivery. Neither deliver out in the countryside but rather pay USPS to do it since they're going out there anyway. They never will because it's too expensive to do so. I suspect Amazon also does the same at this point. The vast majority of all their customers are urban dwellers so they may just add a USPS surcharge where applicable rather than raise rates for everybody.
