A requirement for absolute standards is not reasonable. The following is essentially a cop out & suggests that we should give up on establishing rules for ethical behavior.
Unless we have recourse to absolute standards of 'good' and 'harm', the Golden Rule, in all its variations, is eventually useless.
BTW: I consider ethical & unethical to be less value/emotion loaded words than good, bad moral, immoral, et cetera. Ethical & unethical are more likely to invoke rational analysis. Words like good, bad, moral, immoral tend to invoke conditioned responses.
Any group larger than an extended family requires some laws/rules governing behavior.
It is easier to establish reasonably objective rules/laws defining harmful or unethical behavior than to do the same for rules/laws defining good/ethical behavior. Murder, assault, theft, fraud, et cetera seem like behavior which should be prohibited or at least considered unethical in almost all circumstances. In most circumstances rational people agree with such laws.
What about allowing a family to undergo extreme hardship due to poverty? Should I sacrifice my children’s college education in order to support an indigent family? How much should I cut my own standard of living to help such a family? Why should I be the good Samaritan rather than somebody else?
Should I allow somebody to die if I have a good chance of saving the person? Perhaps you think I should, but what if the person needs one of my kidneys? What if a very large man is drowning? Assuming that I am a very good swimmer, what level of risk should I take to save him?
If I were extremely poor, I would certainly want somebody to help me. If I needed a kidney, I would surely want somebody to donate one. If I were drowning, I would want somebody to try to save me. Does my desire for such good Samaritan behavior require that I be the good Samaritan?
The welfare state mentality seems to be attempting to create the same standard of living for all. I hope it never gets to the point of saying: “You can live with one kidney & you are next on the list to donate to a person with renal failure.”