Looking into this a little deeper and thinking about your problem "logically" I guess (from information gleaned on the net) that Amazon have teamed up with their delivery partners database of addresses and if you aren't on that list it will auto-reject. Your address needs to be accurate to fit their lists (AI isn't in play here yet.)
The databases will probably vary from company from company, so UPS, DHL, Correos, SEUR, etc.. will have their own criteria of where to deliver in this area depending on the cost vs payment for driving up, say, the Arroyo Aceituno which is why so many packets are returned as address unknown/does not exist when you refuse to meet them at Mora Oil or Maloans bar.
It's been mentioned that SEUR for instance get 1 euro per parcel which makes them profitable in city centres but not up here in the sticks.