It's more that Amazon packages can comprise such a a large % of deliveries/orders that the UPS/etc may need to keep that business, even at near 0 profit, to kee

It's more that Amazon packages can comprise such a a large % of deliveries/orders that the UPS/etc may need to keep that business, even at near 0 profit, to keep their infrastructure above water. That contract possibly covers a ton of last mile region they want to cover anyway to stay competitive but couldn't keep going due to lack of volume vs cost without Amazon. It's a bit of a catch-22, they can reform their route and coverage to similarly profitable state with less coverage, potentially dooming them in the long run, or they can take the near 0 profit contract from Amazon and stay competitive while having almost no cards at the negotiation table. Amazon knows their business is huge and needed by these groups and is not afraid to point that out.