"Developed world", apparently, being defined as all countries with a lower homicide rate than the USA?
No. I have not defined it that way at all, as well you know.
There's no standard, agreed upon definition for "developed world", which means you're still cherry picking.
Just because there are different ways of defining developed world does not mean that the concept is meaningless.
I've already given you a number of examples, but let's use Wiki for now:
A developed country or "more developed country" (MDC), is a sovereign state that has a highly developed economy and advanced technological infrastructure relative to other less developed nations. Most commonly, the criteria for evaluating the degree of economic development are gross domestic product (GDP), the per capita income, level of industrialization, amount of widespread infrastructure and general standard of living.[1] Which criteria are to be used and which countries can be classified as being developed are subjects of debate.
http://en.wikipedia.org/wiki/Developed_country
Whatever the debate is, some countries consistently meet the definition and other states consistently do not meet the defintion. Thus, there is concordance, and when trying to analyze something in the social sciences there is very little that isn't a subject of debate. To point to some disagreements and then blow off the whole concept as meaningless is the equivalent of "going nuclear" in an argument.
But anyway, some people such as yourself want to know why Brazil, Mexico, Ukraine, Belarus, Estonia, Moldova, Lithuania, and Russia don't count as part of the developed world.
Earlier I posted the top ten Human Development Index countries. None of the countries above featured.
None of those countries are members of the OECD either.
None of those countries are considered by the IMF to be "advanced".
None of those countries are considered by the CIA as "advanced economies".
None of those countries are considered by the World Bank to be so either.
None of those countries are on the Development Assistance Committee.
None of those countries are in the top thirty of the Economist's Quality of Life survey.
None of those countries are considered by Newsweek to be the in the 30 "best countries" or to have the best quality of life.
In other words, any reasonable metric that you choose sees Brazil, Mexico, Ukraine, Belarus, Estonia, Moldova, Lithuania, and Russia to be not included as a "developed country".
So your claim that I am defining "developed country" as one with "a lower homicide rate than the USA" is false, and probably a downright lie.