this is pretty well aligned with how it works here in the US as well. The idea is literally, anything below 0 f is "fucking cold" and anything above 100f is "fucking hot"

sure, 80f is pretty damn warm, that's how numbers work, they have a range. It's not like there's a distinct point where "hotness" begins and "coldness" ends

90f is generally pretty hot, but it's mostly tolerable, you drink water, you'll be fine, once you get into the 100f range, you start to run into accidental heat exhaustion heat stroke problems if you aren't really on top of it.

below 0f, your nose hairs are basically guaranteed to be frozen, and any facial hair you have is probably going to get frozen over time as well.

It's a heuristic, you're not supposed to treat it as an ultimatum.

I almost never experience below -5C

Okay. Fahrenheit did. 0°F was supposedly based on the lowest air temperature he measured in his hometown.

This isn't about pain points and special clothing, it's about measuring the typical range of climate.