Here's why:
* Shaving only removes the hair at the surface. It doesn't affect the hair follicle, which is where the hair originates and determines its color.
* Hair color is determined by melanin. The amount and type of melanin present in the hair follicle determine its color. Shaving doesn't change the amount of melanin.
* The hair might appear darker after shaving because it's blunt. When hair is shaved, it's cut at a sharp angle, making it look thicker and darker. As the hair grows, it naturally tapers, making it appear lighter.
In conclusion, hair doesn't grow back darker after shaving. The appearance of darker hair is simply an optical illusion.