It comes down to science and diet. Women with more melanin in their skin aka more pigment tend to have "better" or less problematic skin, also melanin which is what determines your skin shade (more melanin the darker, less the lighter) just tends to naturally age less than lighter skin and at a slower rate. Add the diet most of the indian culture follow of course depending on their religion is a mostly vegetarian diet, fresh produce constant vitamins and minerals into the body shows on the outside.