We've already analyzed the differences between lightning and Type-C interface and made it clear that Type-C is relatively superior than lightning either in transmission or charging speed. On the other hand, there also exists apple's product which has already adopted the Type-C interface such as 2015 Mac book and iPad pro. So why did apple's most representitive product: iPhone still stubbornly uses lightning interface rather than give a chance to Type-C? 
First of all, Type-C interface didn't enjoy an unparalleled advantages on mobile phone platforms considering mobile phone relies less on physical interface than its desktop or tablet companion but more inclined to wireless connection. For example, we tend to conduct business presentation or large file transmission via our laptop but hardly through our mobile phone. Thus, a Type-C interface with multiple function seems to be futile in mobile platforms. 
Then, Apple is a relatively closed mobile phone producer in the mobile phone industry considering its closed operating system, independent processor and unique interface which may require unique components and accessories for iPhone. And this unique demand means a huge market revenue and great cost reduction for Apple by adopting the following existing measure. 
To begin with, Apple vigorously conducting market campaign by stressing the unrivaled quality and compatibility of original Apple accessories. This method has been combined with the concord brand identity between apple's product and its official accessories. With the help of these two factors, a great amount of iPhone users will would rather purchase Apple's more expensive official accessories than much cheaper non-official accessories though we should place the doubt on the whether Apple's official cable is indeed durable than others. The next step Apple has employed is to use MFi certification to not only exclude unqualified data cable from charging a iPhone but require a certain amount of fee for any non-official manufacturer who intends to produce a cable which fully compatible with iPhone. Essentially, plugging any non-officially certified cable to an iPhone will pop up a warning which may also hinder you from charging. Currently, the new released iPhone 12 is sold without the attachment of charging cable and earphone. The ultimate winner will always be Apple as this policy significantly promote the penetration of MFi certification. 
Although Lightning port is not as good as type-C port, it should be noticed that most iPhone buyers are attracted by its impeccable iOS ecology and strong performance , and only a few of them really pays attention to the types of interface. Then why should Apple replaces the current lightning interface with Type-C in the condition that lightning interface plays a role as a continuous cash cow? Maybe the next issue Apple needs to consider is how to upgrade the charging speed of a lightning then placing it with another type of interface. 
Why iPhone still adopts lightning interface than Type-C
