Propriety and Developing Countries

At one point they were referred to as the "third world."  As some considered this disrespectful, "developing countries" was suggested (though aren’t all countries developing?  and isn’t the problem just that, the countries being referred to are not developing?).  Some believe LDC (Least Developed Countries) is the new respectful standard.  Others equate such a metric to the "fourth world."  Doesn’t seem we’re moving forward here…