>>a newly built but as yet unnumbered house, and asked the post office what number to give it, they were told not to number it at all, as no one knew how many other houses would be built around it.
Interesting. That seems odd, in the days of GPS, when city planners can easily have a detailed survey of the land from satellite mapping, and when city planning usually requires the entire neighborhood to be planned at one time in order to receive a construction permit.
As I understand it, here when a new neighborhood is built, the developer chooses the sizes of the lots that are to be sold individually, as well as the street names, and the city planning department signs off on it if the lot sizes conform with the planning code. So it's actually the lot that has a number, not the building later built on it, and there are always extra unused numbers between each pair of lots. It would indeed be bizarre if all the houses had to be renumbered every time someone built a new house on an empty lot.
All that is why, in fact, in the US we don't speak of house numbers, but rather street numbers. The number roughly marks a particular distance from an intersection of a north-south axis with an east-west axis -- often Main Street and another thoroughfare, 'downtown.'
Rural routes, that is, people living on farms, used to have their mailboxes just numbered in order of delivery, as in Rt. 3, Box 41 -- so I suppose if anyone ever built a new farmhouse, the numbering might have occasionally been changed. But since GPS and universal ambulance service, they too now have to have road names and numbers.
Not all technological change makes people easier to find, though. In the days of land lines and phone books, all you had to do was look someone up -- I remember news stories, in fact, in the time of the Soviet Union, about how if you were trying to find someone in Moscow, you had to know someone else who knew their address and phone number, as there were no reliable phone books, the concept just didn't exist. That seemed unthinkably primitive to us, the idea that just a residential address and phone number was findable only by word of mouth.
But now, with cell phones replacing land lines, we're headed back in the other direction -- with unpredictable results, as it happens, for both surveillance and opinion polling.