Cool, but a quick search shows that these towers can cool a place by around 10C. So, in the scorching 50C desert, the interior would be above 35C, which is still fucking hot.

A modern home ACs can only cool about 20f below the outside temperature. 50c to 35c is 27 degrees so that’s pretty damn good for a fancy swamp cooler

ok, but the cost of building a quanat is still pretty high and is not trivial to achieve.

Can’t have water flowing everywhere in a country for this to work.

Most countries in the world quite literally have water flowing everywhere already.

But don’t “swamp cooling” systems like the one in the OP not work well in humid environments? Sure, I have running water at home, but I also live in an incredibly humid climate.