Oh, I see. I should just pay whatever Apple says the repair should cost with no regard to reality. If I choose to go to a cheaper repair place, Apple has every right to punish me by destroying my phone. If I don't use touchID anyway so choose to repair it with a normal button to save a few bucks on a feature I don't even care about, Apple should punish me by bricking my phone. Do I understand your point now?
The problem is that reality is shifting and this is the reality of the present. I'm not saying it is ideal, but this is where we are...
Apple has no duty to care about third party parts or third party repairs. If you chose to do a third party repair then it is on you to deal with the fallout of that repair. This is the same in cars, but it is why you'll often see third party shops warranty their work independently of the manufacturer who has no duty to cover their work.
The fact our devices can now be updated after
we purchase them means you have a floating risk as a consumer if your purchase a third party part or get a third party repair. What we're seeing now is why you'll probably see future repairs at reputable shops being warrantied going forward for a period of time.
Apple has no duty to care about your desire to save money. I am not saying you shouldn't be able to save money, but it isn't Apple's job to care about that... This has been established rules or how we do aftermarket repairs forever all across our economy.
The problem with your car analogy is it shades the narrative of the point you're trying to relate it to. Take your Merc key analogy. Wrong key disables Merc. Okay. Still not analogous. The unauthorized part doesn't disable the phone.
The key may disable to car immediately, but if, for whatever reason, it didn't disable the car immediately and it happened a week or month or year later the reality would still be the same. Mercedes would charge you for an expensive repair and fob replacement.
No need to split hairs on this here. The core question is how much of a duty does the manufacturer have to care about third party repairs and components. Established US case law says none. It is the job of the third party part maker to ensure their part meets 100% OEM standards and the job of the repair person to ensure they perform a repair equal to the OEM. If they can't they should refuse to perform the repair...
It would be like getting a part replaced at Auto Zone on your Mercedes and then complaining to Mercedes when the part fails because the Auto Zone tech wasn't able to install it correctly. Re-syncing the TouchID sensor is a key component of replacing it...