with credit/ debit cards.. a merchant can get assurance they are doing the transaction with the correct person because the name on the id will match the name on the card. and so on and so fourth.
but with a gift card.. anyone can use it... it wont matter what ID is used...
how does the gift card issuer determine who bought the gift card who can use it and when it has been used UN authorized?
I never heard of any gift card services asking for ID personally. Usually, people buy using stolen credit cards (doesn't need to be physically stolen, the numbers are more then enough) (carding) and they sell gift cards because It's the easiest thing to get and could get sold for bitcoin which is irreversible, then the gift card will get revoked and no longer works because the real owner of the card contacted the company that issued the credit card and told them that the transaction is not authorized by him.
In other words, the gift card issuer don't know anything. If the company who issued the credit card chargeback the transaction, the gift card issuer will take action based on that, as simple as that.