Golden Rule is not a rule. It’s a code of conduct, even more, it’s a code of virtue.
Not written as “νομος” (law) but “κανών” (code).
A code of virtue, if enforced, loses its defining element: virtue. It's not golden anymore. Just a rule.
The Golden Rule is NOT a contract. No equal participation of volunteers. In that respect, it expects nothing in return.
Example: The Good Samaritan didn’t sign any a contractual agreement when he provided aid to the helpless victim.
The modern concept of voluntary social Contract in all members of the society, as equals, is a manifestation of Silver Rule. But were was the social contract in Rome? In ancient Greece? In India? Limited in certain class, tribe or local region.
ex: Church actively secured (Golden Rule) that in all marriages the bride says “yes” w/ absence of coercive force. NOT in the muslim world, NOT in the indian world.
Black slavery was the product of the enlightenment, the most profitable merchandise that liberals (like T. Jefferson) could buy through adverts that other liberals promoted (like B. Franklin who sold slaves in his newspapers).
There is only one Rule named “Golden” in all European languages. You can’t beat this level of Lindiness without, of course, erasing all European literature.
Those who don't distinguish between "free markets" and "plutocracy" (like Xenophon did) are incapable to distinguish between Golden Rule and Iron Law.
Iron Law: virtue signalling (e.g. Golden Rule) in theory, oligarchic elites in reality
Finally we have to address the paradoxes: every law has a "text" and a "spirit" (paradox 1). Golden Rule is the ideal spirit of law, not the law. Certain slaves liked the safety of slavery (paradox 2) & equity may go beyond its spirit (Iron Law, paradox 3).