When we are surrounded by our luxuries , its normal for us to lose our sense of appreciation of others or other things that we see as 'lower class ' . This tend to lead to complacency , snobbishness and rudeness . We only associate and network ourselves with people on our level socially or economically .
When you have to work 24/7 to provide for your family you don't really have a lot of time to think. When you have plenty of leisure time however one can think about ethics, morals, etc. A good example of this is the Greek and Roman civilizations. Before the rise of these empires there were no breakthroughs on philosophy or governments people had to constantly work. However due to the economical, technological, and political advances normal people had much more time to create numerous philosophies, ideas, and various other things dealings with morals.
Unless you're using your own standard for moral values (Which isn't debatable since they are your personal morals) I don't see how this could be true when ethically speaking advancement in a country tends to lower crime, raise awareness, and produce a more vocal and prolific stance on human rights, general ecology and environmental issues, and standards on what is and is not rationale to allow.
Undeveloped nations generally cannot compete with the well-supplied and advanced educational systems of developed nations. With superior education comes a better understanding of morals and ethics. Many people in undeveloped countries probably cannot even fully grasp what morality even is so why or how would they ponder it? The only way that would happen is if they just happen upon the idea while thinking which would be limited among them. If they cannot understand the concept of morality then they certainly cannot understand ethics. Simple-minded people in undeveloped countries will behave in simple and primitive ways because they do not know better. With that it is obvious who would have the superior morality; those with the superior education and environment in a developed country.
The only reason why advanced countries appear less moral to some is that more crimes are reported as freedom of press also rises with more advanced countries and people are more willing to speak out and report crimes. Less advanced countries have more secrecy and less reporting of crimes, women don't report rape as they are often the ones blamed for their being raped and they get stoned to death for reporting their own rape. So a less advanced country has a greater culture of secrecy.
So the the opinion expressed here is a Myth!