If you are referring to Apple's sending engineers to work out problems and enforce standards you should know that this is not unique to Apple. Huawei does the same with its own suppliers. In my opinion it has much more to do with the fact that Apple and Huawei can afford to pay their engineers much better and hire people with good problem solving skills. It is not that they have some secret sauce and have to teach the factories how to make things. That would be a strange interpretation.