Alessandro Riolo
As a Mediterranean living in an Anglo-Saxon country, I have had to explain this many times over the decades: they build this way for their children. The family will likely live at ground level – or, if they keep animals there, on the first floor – while the upper floors are for married children. In Yemeni culture, likely male children. Yes, the floors may be used for other purposes in the meantime. But that is temporary. The reason they build upwards is that one day the sons will need houses. I would actually bet that, in many cases, you could make a decent estimate of the number of male children by looking at how many floors the house was designed to accommodate.
night brain
Putting a pin into a random part of Yemen (the mountain village of "al-Hutayb", ~$400 GDP per capita, middle of civil war with 6 digit casualties, under constant F35 bombardment) and finding that they somehow manage to construct buildings in excess of 3 stories
