Because it doesn't have the artificial chemicals that are always used in these shampoos. If I could point to a single ingredient that fucks with my hair, scalp, pores then I'd list that singularly instead of saying "40 artificial chemicals". I'd imagine that it's not a single ingredient though. I think that maybe adding in a bunch of unnecessary complexity with a fuckload of ingredients maybe isn't the best idea if you can achieve the same thing with far less ingredients, for a few reasons, but then again I am not a chemist so I could quite easily be wrong there.
You most definatly are not a chemist. Despite what you think, the components in your olive oil shampoo aren't exactly natural either. For example, the olive oil in your products was treated with phosphoric acid, sodium hydroxide, absorbent silica, acid activated diatomaceous earth, enzymes, and preservative most likely extracted from GMO soybean oil. This is all standard vegetable oil refining practice.
There is not a line that defines natural, particularly in an unregulated industry like personal care products and cosmetics, so inferring that the product works for you because it is "natural" and has identifiable ingredients is a bit of s stretch.