Many religions have a position on how individuals should wear their hair, formally stated or not. Even in environments where diversity is thriving, you are likely to see similarities – working within common guidelines.
For those religious groups with strict guidelines, you can risk membership if you stray too far. It can be interpreted as a rejection of a basic tenet.
Hairstyle treatment for men and women, along with attire, can be a very public way of communicating your faith to the rest of the world. It is both a differentiator and a way to identify people who share those beliefs.