Why isn't blonde hair just called yellow hair?

In Scandinavia, we often call “blonde” hair “yellow hair” - that is if it actually is yellow. In my youth we never used the expression “blonde hair” or “blond person”, we used the expression “yellow hair”, or fair/light hair (list hår).

The word blonde has now gradually been taken into the vocabulary through influence from other countries.

https://hairstyle-en.com/yellow-hair-ideas-yellow-hair-dye-trends-new-2021-2022/