[Tam Li Hua]

For the same reason white people are called 'white', even though technically that's not true. *shrug*

And that's why I said "dark-skinned people" rather than "black people". Really, even if one has very pale skin, it's advisable to wear light-colored clothing if one is going to be walking next to the road at night, but it's just especially true if one has rather dark skin.