Under this methodology of all 193 UN Member States – an expansive model of 17 categories, or “goals,” many of them focused on the environment and equity – the U.S. ranks below Thailand, Cuba, Romania and more that are widely regarded as developing countries.
In 2022, America was 41st. Interesting to see where it will be after this term of office, which looks set to be working against many of these aims.
It's not an uncommon view:
Cuba, which was considered Second World but remains Third World economically. - https://study.com/academy/lesson/what-is-a-third-world-country-definition-examples.html Some countries in the Eastern Bloc, such as Cuba, were often regarded as Third World. - https://en.wikipedia.org/wiki/Third_World
That said, developing world is now the more commonly used phrase since it has fewer political connotations, and anyway, this study is specific to Sustainability targets.