@Kayriel While it's true that when one thinks or hear the word "gyaru" or "gal" the first thing that comes to mind is a blond, tanned, flashy dressed japanese (or asian in general, idk if it's also extended outside japan) girl, in reality the gyaru fashion is all about being flashy, that meaning that hair color is just a part of the whole...gals can have all kind of hair colors like ash, pink, light green, ect. but some also leave them dark colored and focus on other aspect (like makeup, the tan or clothing)
Your experience is definitely not wrong, you just probably didn't meet any other.....example(?)....type(?)....idk man, you never saw the pink haired one or the normal haired one lol