Stripping iPhone 13 models down, what iFixit discovered is that Apple has added a small chip (“about the size of a Tic-Tac”) into the bottom of their 13 screens. The chip is a microcontroller which pairs each iPhone 13 to its display. When a display is damaged and needs to be replaced, the microcontroller must be told to pair with the new screen. Doing this requires ‘Apple Services Toolkit 2’ (AST2), an expensive proprietary service which requires consent and certification from Apple.
For those not near an Apple Store, or an authorized Apple service center having the necessary equipment, repair will require sending you phone away. Less competition implies higher priced repair services too.