Amazon has started shifting some demand to it's sorting centers and from there to the USPS - to individual post offices. Maybe this explains the fixed number of

Amazon has started shifting some demand to it's sorting centers and from there to the USPS - to individual post offices. Maybe this explains the fixed number of UPS drivers. The nice thing in this for Amazon , is that this really shortens the delivery distance they need from their external supplier(which means faster, cheaper shipping) but they also have more control on their shipping network, especially around Christmas , when resources are tight and it can cause lots of problems, which means better trust with the consumer over other companies.