I am born and raised in GA. My grandparents, and for many years, my cousins did not have A/C. We just got used to it. Flashforward several decades. We bought an old southern house built in the teens with no A/C. Those houses are built to withstand heat and it is fine until it gets above 90 and then it is just miserable. We lived one year without A/C and it was a scorching summer. The upstairs..used to be attic..is where the kids bedrooms are. That summer they had to come sleep in the living room the entire month of August. If it weren't modern times with crazy people we would have all slept on the porch.
Deee in Oz..my husband is from Oz .. from a cooler region so no A/C is fine, but his parents have moved to Queensland and quite far up. When we go there at Christmas time and the only A/C is in the master suite it is pretty miserable. I usually end up sleeping on the floor to get cool. I have no idea why they live up there, sure wish they would move back to southern Aus.