That people have addresses at all, or can describe their residence in an unambiguous or clear way (even using GPS coordinates).
I used to live in a place I couldn't even remotely give directions to. It was deep within a neighborhood of a poorer country, none of the streets had names, none of the buildings are numbered. I lived in an building where none of the apartments had numbers or names.
If I wanted something delivered, I would go to a local shop for the company delivering it, and show my ID, and they would have it routed there if it wasn't in the building already.
If you wanted a billing address for, I don't know, tracking me down, initiating lawsuits, something like that? I honestly just assume that's impossible.
Furthermore, just because you don't have an address doesn't mean you can't receive mail! At least as recently as a few decades ago, there were rural communities in the US where nobody had a street address; the postal service knew where everybody lived and would deliver mail given just a name and town. I'm not sure whether this arrangement still exists in the US, but I'm pretty sure it still does in Ireland and probably elsewhere.
The push for 911 changed a lot of places by assigning street names, but the 911 folks are sometimes the only ones who know the names. UPS still delivers to some vague addresses on the reservation. Shipping to "House 311 behind the school" does tend to confuse a few Internet merchants.
When I was growing up in the 1960s, we just had a street name (which probably wasn't even required) and RFD #1 and the name of the adjacent town that handled rural delivery for the area. And this wasn't the back of beyond; it was just a couple miles outside one of the main Philadelphia suburban spokes. At some point they gave us a Box number to use although we didn't actually have a postal box and they continued to deliver in the usual manner at least until we moved around 1980.
In the US though, there was a real push to rationalize street addresses for emergency services in the late 90s or so. It may not be universal but I know of even summer camps at the end of dirt roads in Maine that have street addresses now.
How can GPS coordinates be ambiguous? I can see different units of measure/notations being used, and the accuracy might be a problem for extremely close addresses, but wasn't it the point of GPS to provide an exact reference for any point on the planet?
Bingo. In my apartment building none of the units had numbers. I could point you to my unit, which was one of two doors on my floor, the other leading to a unit directly above me. So even GPS + Floor wouldn't quite me enough, although that's close enough that we could figure out who the package was for.
Then the full name should be anough to determine the floor. More problematic though is the inaccuracy of GPS. Where I live, my smartphone's GPS encircles 3 buildings.
In the UK, locations may be encoded as Ordinance Survey map references (I've heard of people using OS references as addresses). It is what most geo databases in the UK were keyed on, until a few years ago.
The OS uses a different datum to the GPS system, so if you convert to lat/lon you'll be out by about 150 metres (where I am, at least). You need to re-project the coordinates onto the other datum to get the real location.
That people have addresses at all, or can describe their residence in an unambiguous or clear way (even using GPS coordinates).
I used to live in a place I couldn't even remotely give directions to. It was deep within a neighborhood of a poorer country, none of the streets had names, none of the buildings are numbered. I lived in an building where none of the apartments had numbers or names.
If I wanted something delivered, I would go to a local shop for the company delivering it, and show my ID, and they would have it routed there if it wasn't in the building already.
If you wanted a billing address for, I don't know, tracking me down, initiating lawsuits, something like that? I honestly just assume that's impossible.