Could this be a case of "I don't think that word means what you think it means"? :-)
De jure "Third World", would mean that the country is either poor, or developing, possibly industrialized[2], and rightfully such[1].
[1] https://www.google.com/search?q=de+jure&oq=de+jure
de jure - denoting something or someone that is rightfully such.
[2] https://en.wikipedia.org/wiki/Third_World
"Because many Third World countries were extremely poor, and non-industrialized, it became a stereotype to refer to poor countries as "third world countries", yet the "Third World" term is also often taken to include newly industrialized countries like Brazil, India and China now more commonly referred to as part of BRIC."
"Over the past few decades since the fall of the Soviet Union and the end of the Cold War, the term Third World has been used interchangeably with the least developed countries, the Global South, and developing countries, but the concept itself has become outdated in recent years as it no longer represents the current political or economic state of the world."
A more serious answer: each country has impoverished neighborhoods. The difference between developed countries and developing ones is the magnitude of the impoverished neighborhoods.
So far I haven't seen any really big slums in Germany, for example.
3rd world means non-NATO aligned states (or communist aligned states).
https://en.wikipedia.org/wiki/Third_World
Unless the US turns communist, it can not be a 3rd world country.