Is this statement not in direct contention with this statement:
>If I were a rightful leader of all Nigeria I would make sure those numbers would never be accessible for westerners as it’s the fist thing you need to know when you decide to wage war of any kind against some people.
Surely the leader of the colonisation target country would like to know the population of the coloniser, so that they can get an understanding of how many soldiers to keep in the defence force?
You need to know military, not population size (how quickly can a militia be raised, how long can it be sustained, how well they are armed, who can be persuaded to defect, etc.). This is related to population size, but not linearly.
Population counts get only interesting for military and tax potential during administration of a territory.
GP's point is valid, though, imho.
You can easily get an estimate of the number of buildings and especially vehicles, which tell you two important things. Not to mention that as a matter of course the first thing to do is photograph everything that looks like a piece of military equipment, which has been a purpose of satellite photography from the beginning.
Various kinds of countries get paranoid about letting people have maps or accurate geographic data. This makes very little difference militarily but causes real inconvenience for the locals.
Besides, nobody wages wars for labour exploitation any more. It's all about what's under the ground.
Anyway with underdeveloped countries - you only need to bribe couple of people and you effectively run the country. Which once again is fixed cost.
That said, my actual experience of processing earth observation satellite images was with scientific data, not spy sats, and in any case it was just over 20 years ago and may be out of date.
What I was working with, any given satellite image capture was a line rather than a rectangle, basically a rolling shutter effect but on a planetary scale and taking ~90 minutes: https://en.wikipedia.org/wiki/Push_broom_scanner