Rusty screw on Apple products

Has anyone experienced issues with Apple alluding to user’s responsibility for rusty screw on iPhone/Apple products?

Context:

I have a shattered back of iPhone and given it’s covered under Apple care the repair should be only for the back part.

However given Apple can’t remove the screws due to the screws being rusty, my only option was to replace the whole unit at a higher price.

I would be interested to know if this has been a common recurring issue for Apple users, with general use (especially without water immersion/exposure—given one of the staff told me it would be due to water exposure despite Apple iPhone had IP rating + I have never exposed my iPhone to water).

It’s also sad to know that such premium brand (or maybe not anymore) uses material that corrodes easily and subsequently put it down to user’s responsibility.