Or do they???!!!
Natural teeth color isn’t white, so anyone with white teeth has had whitening treatments or sonething else to brighten their teeth.
They drink coffee or tea and then have their teeth whitened. Or they don’t drink coffee and tea to reduce the amount of yellowing, requiring less whitening. Or they have veneers.
I’ve seen pictures of tribes of people who mostly have perfectly white, straight teeth. It’s possible under the right circumstances of diet, youth, and genetics.
Super misleading: https://adventure.com/wodaabe-nomads-gerewol-chad-africa/ They aren’t as primitive as you make them out to be and they use techniques to specifically show off their white teeth. The fact that their canines are flat should already be a big hint that they don’t have natural teeth.