And a lot of them don't?
A lot of people who work on a computer all day also have back pain and inflexible schedules. Hell, I'm sure a lot of knowledge workers in other countries work in places with no air conditioning, for example - not exactly "extreme" but not climate-controlled, either.
It's totally, completely, fully different.
Have you ever worked as an electrician/plumber, etc.?
The amount of physical stress, sweat, exposure to bad weather, etc. are orders of magnitude higher than what you get as a tech worker, even in 38°C heat even without an AC.
Your comment reads like it's coming from someone who never ever worked physically even as a volunteer/for fun.
Any non-trivial amount of physical work will tell you that it’s many orders of magnitude tougher than working with computers.
The worst part is you gotta show up and work your ass off even when you have flu, or something like that, or you lose a day's wages.
Marimba Ani's seminal work Yurugu is a sociological study of this culture from a non-western perspective. I can't recommend it strongly enough if you want to understand the nexus of social/psychological/epistemic factors that sustain the "us" vs "them" thought pattern and its corresponding cultural manifestations.
https://archive.org/details/yuruguafricancen0000anim/page/n3...
No, us vs them is an innate aspect of human psychology going back tens of millions of years. It is found in literally every single group of humans that numbers more than 20.