Sure white people can go to any barber and be sure they have been trained in straight hair but that is not the point. White people with extremely curly or frizzy hair are also poorly served by society.

So people of African descent have a skill gap to contend with, on top of prejudice to negotiate, and hair becomes a political thing where community needs to close ranks.

Why is it a more meaningful relationship than for non-blacks? Tradition on top of comfort and security, and a layer of "insider knowledge."

Getting huffy about it is pretty cringy, though, and I wish you were more open to learning.