It's 93 here today and I'm not using the AC, haven't turned it on for several weeks. That's because it's autumn and the hot days are fewer and further between now, and the lows are getting down into the 50's so in the house it's only 78 right now (which is comfortable for me, that's what I keep my AC set on during the summer). If it was 93 but August instead of October, you can bet I'd be using the AC. The overnight lows at that time of year don't go below the 70's and the house would never cool off to 78 without it.

Point is, the US is a very large country with lots of different climates, which the people who live in them are acclimated to. Northerners are acclimated to the cold so the 70's feel very warm to them, while they feel perfect to me where I live. In even hotter areas 70 may feel cool. Of course that all depends on the humidity as well.

I lived in western Montana (cold and dry climate) back in the 80's. I don't know how it is there now with climate change, but most people didn't even have air conditioners at all back then. There was no need. Even in the hottest part of the summer it got chilly or even cold at night. The house would hardly have time to heat up, you could regulate your inside temp with strategic opening and closing of windows at different times.