Well, the main advantage I was pointing out about a gift card in that case is it allows privacy. It allows someone who would normally need assistance to get what they want to get what they want without having to tell anyone. That niece, at the time, was in her later teen years, so the ability to just pick whatever she wanted and get it for herself might be actively appreciated. I don't know if it was, but it strikes me as a benefit to gift cards for a particular age range. Not generally relevant, and I generally dislike gift cards, but potentially useful now and then.

If she needed to kick in more money she probably needed parental involvement, although I don't know whether it'd have been her money or theirs. Weird transitionary ages.

She'll be starting college next year. She'll probably be having her own bank account soon if she doesn't already. Then it'll fall back into the standard issues with adults and money would probably be distinctly better.