With Apple, the reason is usually security. For a third-party screen, it could take pictures of the display to steal information. With the iPhone being the targ

With Apple, the reason is usually security. For a third-party screen, it could take pictures of the display to steal information. With the iPhone being the target of state sponsored brigands, it is not theoretical. It is probably happening. With the camera modules and batteries it’s a question of calibration and Apple clearly never thought anyone but them needed to calibrate the part.