COUPANG’S OFFICES in Seoul afford a view of the South Korean e-merchant’s promise. Every dawn the forest of high-rise apartment blocks teems with its vans dropping off orders made the night before. This self-styled “rocket delivery”, and Koreans’ love of it, fuelled Coupang’s stratospheric rise. When it debuted on the New York Stock Exchange in March 2021, its shares nearly doubled in value in an instant. It closed its first…