Because membership of a group, especially for marginalised and oppressed peoples, is a way to have shared strength and be able to relate to others' experiences and protect each other. Which is an incredibly powerful and necessary until the world is significantly fairer.
Also in the case of barbers, it is plainly obvious: Experience working with hair of a certain type.
Also in the case of barbers, it is plainly obvious: Experience working with hair of a certain type.