but surprised nobody has brought this down to contract law. Are you folks telling me there's no limitation of transfer in the fine print when you buy one of these cards? That would seem to be the first thing at hand.
However, if given as a GIFT, and the recipient has no idea a contract exists, per law there is no contract. So Walgreens basically got themselves in this pickle. We note that OP didn't get arrested or charged and it would have been disastrous for them to press anything.
We are left with our usual dissipation into "ethical" arguments. But people regift things and sell things at garage sales. Some people are expert garage salers and they can furnish a whole house for pennies on the dollar. Does that make them frauds? Some of them resell these objects. Same question. I'm really not seeing any major ethically defensible grounds for Walgreens here.
Hidden Harvest: Long Term Food Storage Techniques For Rich And Poor is a great ebook for beginners and advanced food storers of all budgets or no budget at all.