This is all over the (Jewish) interwebs and I even got a call about it. This guy has the nerve to tell (not ask) me I must give him the $25 donation, what chutzpah! I have enough cards that if he asked nicely I'd actually consider it.
Who said you must give anything? "you can", meaning if you would like.
Its an opportunity that a lot of mosdos are trying to capitalize on.
Yes, anybody can go buy store credit at a local grocery, but there are some generous people out there that wouldn't mind throwing 25 bucks to charity when it doesn't cost them a penny.