Growing up in California, hardly anyone I knew had air conditioning. Neither of the houses I grew up in had it.
Public spaces are a different story, but none of my schools had AC either.
My apartment didn’t have a/c. I hated the Summers there.
I’m guessing you didn’t grow up in Fresno. 
Ha, no. The Bay Area.
Ours is a maritime climate, without extremes of humid heat or dry cold. Continental Europe (especially when you get far from the sea) will have these greater extremes.
Europe is quite a big place with a diverse climate. I don’t have any need for it in London, but my holiday home in southern Italy has it.