In the United States, a zip/postal code covers a town or multiple towns. For example, I live in a town which has two zip codes: I use one of those two, while the areas to the east of me in my town use the other zip code. Not every house has its own postal code, but they do have addresses, and subequently, address numbers (e.g., 5 John Road). The status quo of assigning a "postal code" to every building/major area on the map is a thing from voice roleplay and is not realistic.