Cannot Gift App Using Apple ID Credit; Charges Credit Card Instead

Summary: Why can I gift Apple Credit to someone but not gift an app without it charging to my credit card?

I gifted an app several weeks ago while having positive/sufficient credit on my Apple ID expecting my Apple ID Credit to be used as with all my other previous purchases. I also have a credit card linked to my Apple ID Account.

I was surprised to find out that for this purchase, the payment charged instead to my credit card.

The "manage payment section" of Apple ID specifically states "your Apple ID is used for each purchase first until it reaches zero."

When calling Apple Support, I was instructed that under Terms and Conditions that Apple ID Credit cannot be used for gifting. Additionally, to obtain a refund I would need to withdraw access to the app.

Can someone please show me where this is written?

It does not follow that I can gift Apple Credit to someone else but not an app. This appears deceptive at worst and inefficient at best.