Kristin,

Yeah, it's definitely trickier.  That's why the usual error is so common.  I think the flaw in the Golden Rule is ridiculously important. It's not much of a stretch to say that the entire book is about that.

And your comment about gift-giving reminds me of a very useful application of the Platinum Rule: love languages.  A common case of the usual error is to assume that someone else's love language is the same as yours, so you try to express affection the way YOU'D like to receive it instead of the way THEY want to receive it.