Utterly stupid little things, its money that is less useful in EVERY situation and expires! Even at the store where you can use it, what do you do with the money that’s leftover but too little to spend? Especially at expensive places, you could very well end up with 10-20$ OF YOUR OWN MONEY, that you can’t even use!
I was given a dunkin giftcard for volunteering at a repair cafe. First of all I’m on a diet but secondly I stuffed it in my wallet so quickly I completely forgot about it. The day I remember and go through the trouble of attending such a wretched establishment I was told it expired after I finished giving my order! After such bother to try to use this cursed thing I refuse to return fruitless from my endeavors so I paid with my own cash.
It is now, sulking into my hashbrowns and Boston cream do I realize I am now poorer, fatter and fucking miserable. FUCK gift cards.
Gift card money is invested same as sales, it rings up the same. This stuff gets sloshed together in the overall balance sheet. It amounts to probabilistic overpaying, where one person might spend their whole card immediately (no overpaying), another takes their time using it (overpaid at the rate of inflation), and another forgets about it, loses it, or just never spends all of it (overpayment by the amount left on the card).
You could also think of it as zero-interest debt issued by the purchaser to the store, payable in future purchase credits with the onus on the lender of the debt to collect later. As you note, the store can invest the money immediately so it is guaranteed profit.