China is the second richest country in the world. It has the most billionaires, and has experienced steady economic growth for decades. It baffles me that people still classify them as a developing nation.
Shanghai is modern. Huge parts of the country are developing.
Whether a country is developed or not is defined based on their standard of living per capita, not their absolute size. A country with a billion poor people has completely different social, demographic, industrial and political drivers than a country of 300m high I come people.