AFAIK; the pieces where lots of people tend to die from heat waves in are the places where there isn't a regular annual need for AC.
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.
Nearer to the equator pretty consistently means less seasonal variation in temperature, it does not mean higher summer peak temperatures.
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."
Where there are delays, they aren't necessarily “a few days” but months, and, yeah, life in, say, California's Central Valley in a hot, dry summer without AC is somewhere between unpleasant and intolerable.
I live in Michigan -- about once every 7 years we get unseasonably warm summers. It's been 85-95 degrees through June with the sort of humidity that makes it feel like you have to actively think about breathing.
People die from heatwaves; modern conveniences like A/C make that sort of thing a lot less common these days, so while the original comment writer's attitude that "modern life is no longer possible" may have been meant to poke fun at "first world problems" -- yeah, I get it, we all have it pretty good -- these "conveniences" do more than just "make quality of life a little better"[0].
[0] Not saying there aren't downsides, either, but I'm not willing to give up my A/C for 'em.
We visited the UK in late May during one of those heat waves and got stuck on the London Underground in a very hot train. Lots of fun!
There are greater economic threats pushing people into these skills.
Personally, since I have them, I am happy to share with others during these times. Just good to know. And one never really can know when it all will matter.
Either way and in any case it is worthwhile learning what is being done, even if only to make sure corners aren’t being cut.
It's typical if this is the rule for a tradesman to refuse to sign off on work, or charge you a high fee to do so.
In any case, it means "you can do it yourself but..." is pointless.
Getting major work done without a license seems like a great idea until one tries to file a major claim with their homeowner’s insurance.