Why are some shampoos better than others?

A lot of the shampoos sold in health food stores have made my scalp itch, my hair waxy so that it sticks together and afros out, and have left major soap residue all over my hair that flakes off when you brush it. They also made my hair hard to untangle. Doctor Bronners, Alaffia, and several others that I’ve tried over the years are all like this. I read somewhere this may be because the soaps are not pH balanced, and using an apple cider vinegar rinse (or anything acidic) after shampooing will solve this. Not sure if it’s true.

On the other hand, some brands like Clean Kids Naturally by Gabriel Cosmetics Inc, do not. It is a shampoo marketed for babies. The ingredient list is very short, no sulfates or other “bad” ingredients, no waxy residue, no flakes, no itchy scalp.

No shampoo, in my experience, can compare to the Shu Uemura Art of Hair line. This thing is full of questionable chemicals, but it makes my hair look fabulous.

Will someone please explain the chemistry of soap and shampoos so that I can finally understand WHY this shampoo is so effective while many others are not?