> and even within a country there are often many different conventions.

You know who knows this? The tax authority.

> the local operators usually have enough understanding of the local system to get the item to its destination.

Large freight does not work this way. I worked on top of a ski resort for a while. We had a mapped address right where the ski left let out instead of the base of the hill. In the summer you could drive up to it on an ATV easily and a pickup truck if it hadn't recently rained. Somehow a semi truck driver for a freight company got this address and mapped a route to it. We were quite surprised to see the 53' box truck driving up the side of the ski hill.

> it's probably not feasible for a global product like Google Maps to understand and encode every regional system.

The information is encoded elsewhere and it's a bummer there is no incentive to make it as open and widely available as is possible. Although if delivery can rely only on partial information to "complete the next leg" then why can't address lookup do precisely the same thing?