When I was growing up we didn't need it at all, however within the last couple of decades the temperatures have really ramped up to noticeable degrees. There are parts of my house which have gone to 30c, which never used to happen.
I have invested in two air conditioning units, however it's just an added expense that feels like patchwork (given projections of climate change getting far worse).

Nope. We don't even all own electric fans.

When the typical temperature is less than 18C yea you don't need it. Up until now you'd maybe get a few days and the cost was not worth it. Most people would think it's better to spend the money on insulation for when the temp gets low.