Yeah, 40C sounds just absolutely awful, I'd much rather put up with -20C… and only a little bit because several cars have had air conditioners die on me. But yeah if it's above 0 seat warmers can be a bit luxurious, but aren't worth adding.
I think people who haven't lived in north central/east North America can really underestimate how brutal the winters get there. Not like I can judge, I only know how bad y'all's summers are because of the natural disasters relating to it.
Seat coolers are a thing these days! They use peltier coolers, which are solid state but worse than the refrigeration cycle. It's still luxury, but it's now "luxury trim on a prius" luxury as opposed to only in luxury cars.
But yeah, the major car brands being based in the US (largely in the aforementioned midwest), Germany, Japan, and South Korea really doesn't do favors to folks from warmer climates, and it's easy for the world to forget about your UV issues.
Do you not have harsh winters? I don't miss them that much in the American pacific northwest (mild 4 seasons climate) outside of a few weeks a year, but when I lived in the American Midwest where the climate is harsher in both directions I really missed having seat warmers when it was below -5C regularly and sometimes going below -20C
Yeah I couldn't learn if I took a laptop out in class. I only got it out when the class time was spent on a project. Honestly switching to a desktop my final year was probably better for me, it led to me spending my computer time in labs or home instead of having every distraction every time
Yeah in high school I would get migraines from dehydration which is a problem because drinking is repulsive to me when I'm nauseous and in pain