Ok - so probably not a scam, thats an exaggeration, but got your attention.
How many people grab a gift card for say $100, buying it via a % off deal but then only spend $95 at a shop they’ll rarely buy from again.
I did it for kmart and have $4 left but can never be bothered to remember to bring it along or the myer card with $5 left but never really shop at myer.
First world problems and poor planning is probably the answer.
I once had $0.07 left on a Coles group gift card. Found out a friend was headed to officework for something and I insisted I come along and they use the gift card despite their protests. She was embarrassed to say the least and explained to the cashier I was making her do it LOL. I've never not used the full value of a card.