Here a little drawing to help you understand :
1034 --------- 1036 --------- XXXX ---------- XXXX ---------- 1042
The two houses in the middle are 1038 and 1040.
Yup. With some streets, this works, but some just don't have numbers. Determining the street name can be tricky too: That's probably the street or intersection that has the main entrance or most prominent corner store, but in a few cases, that's hard to decide. The convention I used for intersections is alphabetically by type of street, then street name (Aves before Blvds before Drs, etc). But of course, this is totally arbitrary, and none of this has to be 100% consistent, as the main focus of the whole thing remains matching landmarks, not their addresses.
Also, good spot lxr ! That district was a bit empty that's true.
BTW, who added ingame landmark that doesn't seem to have a real life match yet ? And why ?
I added a few (very few) as a kind of bookmark, where a building is so distinct that I'm certain it can be found (some of the skid row finds were such bookmarks).
It's a software issue, I guess. Probably, landmarks that don't have a match yet should only be visible when logged in.