In this thread, a fundamental misunderstanding of how gift card market works seems to prevail.
There’s basic arbitrage. Vendor Acme in region X locks out people from region Y (e.g., based on payment method address); Alice lives in region X and can buy an N value Acme gift card for N-1 at a local store; Bob lives in region Y and wants to transact with Acme; Alice buys a gift card for N-1 and sells it to Bob for N+1 online; Bob gains the ability to transact with Acme, Alice gains 2 as revenue.
Thus, gift cards going for higher than face value does not automatically imply anything beyond a market acting as it should and is not specific to Amazon in any way.