*Edit: I checked some of the stuff more out in detail. While some concepts on this are valid and backed up by sience, others like RSD are not. Use this as a springboard for learning, not as a valid source in itself. Yes it says so in the corner already. But spelling it out might help.
People are more complicated then a diagram from the internet. Never forget that.
I think “Highly developed morals” in this context doesn't mean being a "better" person by following a "superior" code of conduct.
It means a higher chance to follow any established code out of principle - even to one's own detriment - even with zero chance of getting caught cheating - even without getting to have bragging rights on upholding integrity. (But only if that code is properly understood first and deemed reasonable. Arbitrary BS-rules don't have that effect) There was a study about it, I think, from Bazil?