Yeah the reason i susoect thag their literacy rate was artificially low becuase education was extremly restricted when the japanse ruled korea. Or else them going from a 22% literacy in 1945 to a 88% literacy rate in 1970 (something that has no other example of existing) would be impossible . Also Singapores case is somewhat exaggerated. While they weren't rich or devleoped in the 50s. They still had the highest gdp per capita by far in southeast asia and were the most developed in that region.
South Korea was basically neglected and North Korea contained basically all of Korea’s manufacturing and heavy industry set up by the Japanese when they “annexed” Korea. Most of this was extensively damaged during the war but the USSR spent a lot re-building it.
Singapore continued to build on the British making it an important international trading port and as a financial intermediary shipping raw materials such as rubber, timber, and spices from the Southeast Asian in exchange for finished goods from both within and, especially, outside the region.
It's was the completely the opposite for Somalia, not only was our trade forcefully appropriated or disrupted but the British destroyed/dismantled key industries/manufacturing plants in the northeast and south and the southern banana export rail way right before independence.
This is why Somalia started out with less wealth and lacked state capital when it first formed as a government. Had to build up new industries and wealth.
Japan was actually one of the most urbanized regions in the world actually. Tokyo/edo was the largest city in the world in 1722 with over a million people living in it. Around the 1600s they experienced a massive boom from the peace of japans reunification. They also had some of the highest literacy rates in the world right before the meji period. The fact they could reverse engineer European technology with a couple of years of the europenas forcing open Japan in the early 1800s . Shows they weren't really that behind at all.
Those cities didn't really have paved roads, railroads, plumbing electricity, factories, non-agricultural industries, deep water ports , modern educational systems and banking etc. Japan was playing catch up as it was still stuck in middle ages when most of Europe and America had emerged out of it almost a century prior.