Have a friend whose father was scammed out of thousands of dollars. The ploy was that an "attorney" from another state called to say how the college-aged grandson was in trouble and that the fastest way to make bail and retain said attorney was to purchase thousands of dollars in gift cards that are redeemable online and then read the redemption codes off. He ended up buying something like $15k in gift cards in one place and read them off, and sure enough the scammer hung up right after getting all the info.

It all sounds obviously fishy to you and I, but an intelligent but panicked elderly man concerned about his grandson's wellbeing fell for it. They don't need very many victims to make it worth their while.

They required you to sign a form that you wouldn't trade it for goods or services? Did you sign it? That part feels like the scam.

No, they asked me to sign a form (on an iPhone, FWIW) stating that I knew that strangers calling out of the blue and asking for payment in iTunes cards was a scam.

Doesn’t that violate the first sale doctrine?

How exactly? Apple doesn't prevent the sale, it just educates the purchaser who then acknowledges that they were warned.

The way OP worded it, it sounded like they (Apple) were saying, “you agree not to ‘give’ this card to someone who is a scammer”