Nearness to the equator is not the only relevant factor to the importance of AC. If you turn off the AC in many places in the USA in the summer, lots of people die.

Latitude isn't the only thing that determines climate. Phoenix AZ is a lot hotter than Ecuador, Kenya, or Indonesia.

Also, this isn't just about cooling; it's about heating, too. Imagine living in Saskatoon SK without a working heat source. Nobody does that. If you're not relying on electric/gas heat in such places, you're relying on fire.

One important factor is that there are design decisions made which are optimized for air conditioning such as buildings without any windows that open.

Im from a tropical country and houses are built with consideration for airflow, such as concrete walls with no insulation, gaps in the roof, etc. Also, days are shorter(no 8 pm daylight). American suburban homes are built with central AC in mind of course I dont expect people to know how to deal with heat without experience living in hot countries.

> There's at least a billion people that live nearer to the equator than anyone in Europe or the USA and don't have air conditioning.

Nearer to the equator pretty consistently means less seasonal variation in temperature, it does not mean higher summer peak temperatures.

They're also less economically productive than people in cooler climate or with air conditioning.

Lee Kuan Yew, founder of modern Singapore: "Air conditioning was a most important invention for us, perhaps one of the signal inventions of history. It changed the nature of civilization by making development possible in the tropics. Without air conditioning you can work only in the cool early-morning hours or at dusk. The first thing I did upon becoming prime minister was to install air conditioners in buildings where the civil service worked. This was key to public efficiency."