Apple Giftcards VS Appstore & Itunes Giftcards

I recently received an 80 AED gift card as a gift, but when I attempted to redeem the code, it did not work.

I have been in contact with support for approximately two hours, but unfortunately, I have not been able to resolve the issue.

One of the specialists I spoke with suggested redeeming the card on the actual Apple Store website or using it directly through the Apple Store. This leads me to question whether there is a difference between the types of Apple gift cards and why they cannot be redeemed universally across different methods. Specifically, why is it not possible to use the card interchangeably for both Apple ID payment methods and Apple Store credit to purchase products such as iPhones or AirPods?

This is not a complaint, but rather a question and a suggestion for Apple to consider. Allowing customers the flexibility to use gift cards seamlessly for both Apple ID payments and Apple Store purchases would greatly enhance the customer experience and simplify the redemption process.