According to Wikipedia,

A developed country (or industrialized country, high-income country, more economically developed country (MEDC)) is a sovereign state that has a high quality of life, developed economy, and advanced technological infrastructure relative to other less industrialized nations.

If we consider four Asian Tigers + Japan as outliers, there are no countries outside the European descent that reached developed status.

What is the core (low level) reason behind this?

Changed status to publish