Awww, look at you comparing temps on the cool coastal fringes of the Pilbara.

The interior gets hotter, Marble Bar for example.

> Pilbara is sparsely populated, Arizona's had much larger urban centers since the 70s

I fail to see how this is relevant to the design of individual buildings and the choices regarding passive Vs active cooling.

> A couple years ago Phoenix saw daily highs of over 43 for a month straight.

That occurs roughly every five years or so in interior (not coastal) Pilbara locations.

This year a W.Australian wheatbelt town much further south (cooler, and not in the Pilbara) saw a month of ~ 40 temperatures peaking at 45 .. a month of over 40 in the interior is expected yearly.

> It's an unforgiving environment, and while there were people who lived there in pre-Columbian times they didn't do so in large cities.

Much like the Pilbara, save for the "pre-Columbian" marker - before European colonization people lived in all parts of Australia, including the Pilbara, the Tanimi, and other desert regions, for tens of thousands of years.