Doing unto others as you would have them do unto you is an old adage that works every time because every human wants to be accepted and treated in a win-win manner.
The adage of “do unto others as you would have them do unto you” is called the Golden Rule and while it is found in philosophical and religious teachings, it can also be found in the evolution of mankind. Our early ancestors lived in tribes and were very territorial, with a strong sense of “Them and Us.” But at some point, some of these small tribes that historically fought one another began to cooperate and work together sharing their knowledge and becoming more successful as a species. So in a way, because cooperation was a cause of modern humans (homo sapiens) becoming the dominant species among many hominids, this principle helps define what it is to be human, and by violating it, you are reverting back to the beast within you.
Neanderthal man is a classic example of similar humans who were notably reclusive tribal warriors who failed to survive when their environment changed, while Homo sapiens who lived in the same time and place survived because they worked together for the common good. Cooperation is essential to success, and no man is an island unto himself.
Cooperation also breeds respect and with respect a trust is built that bonds the relationship, which makes this one of the most important principles we need to follow. If that trust is broken, it is because someone violated one or more of the four principles; Causal thinking, Responsibility, Honesty, Cooperation. In fact, if you violate this principle, you probably violated all of them.