There are a ton of different variations of the golden rule that mostly have slightly different implications. Pretty much every religion has some flavour of it, and there’s a good reason for that.
Cooperation has for a long time been a necessary part of human life if one wishes to accomplish much of anything, and the golden rule has long been a building block of cooperation. Of course, it’s not particularly scientific and it’s precise implementations, as you’ve noticed, are either vague or not fully correct.
Enter game theory. The prisoner’s dilemma problem is a model cooperative game that explores various behaviour patterns between two parties. As it turns out, some of the best strategies to maximize personal gain given other opponents with unknown strategies are called: “forgiving tit-for-tat” strategies.
Basically, cooperate until you’re betrayed, punish betrayal, but then return to cooperation. I think if you squint a bit, you can kinda see how there’s similarity to the golden rule.