Every child foot is different. How can one shoe help all those different types of feet?

First, we need to accept that there is only one perfect alignment on a foot and all other foot types are deviation from perfect form.  The reason we can claim that our shoe will help, regardless of foot type is simple. In children, the bones are not ossified yet and have a large amount of soft cartilage. The foot starts to ossify (and fuse) the bones at about 8 to 10 years of age. Once the bones ossify, we can not correct or align anything. However, before the child is ten year old we can guide the soft, growing foot into the perfectly  aligned form regardless of how deviated the foot is from the perfect ligament. After ten years of age, this is not possible. This is the reason why all the children should use our shoes also. Suppose you have a child that has perfect alignment at birth. You would want to maintain that alignment and not use shoes that might guide your child's feet into an incorrect, mal-aligned  shoes. Since there is only a  relatively short window of opportunity to affect the posture, you should take advantage of it.