To my best knowledge scammers ask for Itunes, Amazon, Vanilla, PayPal cards because those can be used all over the world online by activating them and use PIN codes on the back of the card - no questions ask. They can be used for cash advances at ATM or purchases online. Other gift cards purchased in US must be used online or retail shopping within territorial US area . Also the cards which can be used all over the world are reloadable and scammer may ask next victim to refill the gift card online. When victim will agree to do it , info online will show the location where card was purchased ( US) but not the location where money was spent or merchandise shipped. Scammers try to be very clever but fortunately for us they are not.
Tips to avoid becoming the victim of a scam
If you are NOT purchasing an item from the iTunes Store, App Store, iBooks Store, or an Apple Music membership, do NOT make a payment with iTunes Gift Cards. There's no other instance in which you'll be asked to make a payment with an iTunes Gift Card.
Do not provide the numbers on the back of the card to someone you do not know.
Immediately report potential scams to your local police department as well as the FTC (ftccomplaintassistant.gov).
Confronting the scammer is WRONG!!! DON'T enlighten criminals with your wisdom. REPORT & BLOCK.
PHOTO VICTIM - "Do not confront the owner of the pictures, as they are victims themselves! You will only serve to further the terror and harm !" Silence Is Golden!!! I speak Polish.