I spent time thinking about this.

I think this is the closest to "absolute moral truths". People discover these because these are not some arbitrary rules, the are actually absolute, universal laws.

People understand subconsciously, for example, than a person that does good for no reason expresses higher form of being good that a person that does good in exchange for some kind of benefit.

It doesn't mean that mutually beneficial relations are not good, the society is basically built on spoken or unspoken contracts.

But we understand that a person that does good altruistically, not expecting any benefit for it, is much more likely to be trustworthy in all situation. And a person that does good expecting benefits may (not must, just may) turn on you when they stop seeing benefits.

And I think the same goes for countries.

When we see US performing their foreign relations game but only ever putting their weight when we can later find they were expecting some kind of benefit, and almost never for countries that have nothing to offer, it becomes transparent to us that US is basically much less likely to be trustworthy than if it did its actions based on principles.

And in the US "a friend in need is a friend indeed".

And the UK also, although I think you need commas to make the meaning clear:

A friend, in need, is a friend indeed.

Also the english term "fair-weather friend" for friends who aren't around when times are difficult.

Italian too, "gli amici si vedono nel momento del bisogno" - you see real friends in the hour of need.

French (at least in France): "c'est dans le besoin que l'on reconnaît ses amis" (nearest well-known English saying: 'A friend in need is a friend indeed').