Currently Amazon "owns" the customer, plus it owns very large fullfilment network - i.e. a caching for the physical world - making it's cost per packet the lowe

Currently Amazon "owns" the customer, plus it owns very large fullfilment network - i.e. a caching for the physical world - making it's cost per packet the lowest. This is a powerful combination. Furthermore, if Fedex/UPS will start to find sucsess in this "prime" project, Amazon could instantly change it's software to add a box "only from branded manufacturer's store", or some other software change, and solve this hit and miss experience you speak of.