If a product is used by everyday consumers it should every time it passes from technician to consumer when acquiring or repairing be fully inline with all the harmonized standards the device shipped with initially.
I'm not sure what you are advocating. Are you saying that anyone who repairs any device should submit the repaired unit for full certification testing of every standard that the original item was required to meet? So that if I replace the bumper on your car, I have to perform the full suite of destructive crash tests?
Or are you saying the repair should be done in a manner that reasonably ensures conformity with the original standards, with limited testing appropriate to the situation? After all, as I believe you pointed out, the original manufacturer's conformity testing is done on a sample, then uniform manufacturing practices ensure conformity of the entire production batch. The car company crashes one car to test the bumper, then assumes the rest will work similarly. The same would apply to repairs, would it not? If I replace your bumper with a proper part and install it in conformity with the manufacturers procedure, it should be good? Same-quality replacement parts and proper procedures, right?
What better way is there to achieve that then to mandate the availability of those parts and procedures? Your top post shows what you seem to think is an awful bodge (although it likely is good enough for any reasonable purpose) but ignores the fact that the availability of that part would have allowed for a nice, neat and completely compliant repair. I'm not necessarily arguing that Apple should be required to supply that part if they don't replace it themselves in their repair shops, but I think its pretty clear that withholding OEM parts is going to create a market for questionable quality repairs.
That is or should be the law.
I don't know where you are, but here that is not the law nor is it likely to become the law. Laws requiring inspections of furnaces, cars, etc. are very unpopular and seen, IMO mostly correctly, as supports for trade unions and business interests. People don't like being regulated, but they don't mind regulation of others....