FWIW, one of the gift card review screenshots doesn't appear to support the claim that the seller is offering gift cards for reviews (not that more evidence of that really seems to be necessary). The circled section of the review is "I won an Amazon Gift Card at work", and it doesn't mention getting one from the seller.
> Now the question is how this seller is getting the buyer’s address.
The card offering the gift card asks the buyer to send their order ID and a screenshot of the review to a given email address. If the gift cards are sent electronically, they wouldn't need any further information, or if sent physically (which I doubt), they could just ask the customer directly. They don't need to get this information via Amazon if I understand things correctly.
> Now the question is how this seller is getting the buyer’s address.
The card offering the gift card asks the buyer to send their order ID and a screenshot of the review to a given email address. If the gift cards are sent electronically, they wouldn't need any further information, or if sent physically (which I doubt), they could just ask the customer directly. They don't need to get this information via Amazon if I understand things correctly.