Why should they be available for 3rd party repair? If ifixit wants to do a teardown of the devices and document them then that's fine. I think it's completely reasonable for Apple to require a certification in order to get manuals, parts, and schematics. When something like a cheap, third-party screen replacement inevitably ends in an "iPhones suck, mine misses my taps and shuts off randomly", it's Apple that looks bad, not the 3rd party kiosk that uses shit components.
The solution to this is simple, the device could cryptographically verify the parts in it and if it detects a 3rd party part then on boot it shows a message saying "An unofficial touchscreen is installed" then the user knows if the touchscreen is working shit its probably because of that and if you sell the device the buyer knows what they are getting.
This is already the case. TouchID will disable on a device with a screen that is not re-keyed. Your solution isn't simple at all because it doesn't actually address the problem.
It does. Touch ID is just disabled and a message pops up saying that the display key doesn't match the Secure Enclave and that Touch ID has been disabled.
