> effectively everyone lives in a city in the modern world, and while their housing might not be air conditioned most of the major buildings are.

The states of Rajasthan, Madhya Pradesh, and Uttar Pradesh lag the rest of the nation in economic development. This statement is very much not true in those places, and even elsewhere in India. Air-conditioning is still a luxury outside of relatively well-off people's houses, corporate buildings, and malls.

> Cooling ourselves down in a heat wave, in the modern world, is a solved problem at least as far as keeping ourselves alive goes.

People there can't afford to not work. Sitting in an air-conditioned space for half the working day 4 months a year is not viable for them. A lot of the work is manual or farm labor that must necessarily be done outdoors.