South Korea was under varying levels of dictatorship from the Korean War until the Sixth Republic in 1987. Roh Tae-woo, the first president after authoritarian rule, was imprisoned for corruption. Roh Moo-hyun, the President from 2003-2008 was investigated for corruption and died by suicide rather than face charges. Lee Myung-bak, his successor, was imprisoned for corruption. Park Geun-hye, his successor, was imprisoned for corruption.
I don't know that South Korea is the poster child for a "better-run and not not-so-corrupt" society.
It's not a poster child, but the US sets such a low bar that SK looks great by comparison.
Note also that the US isn't so visibly corrupt at the federal level; it's at the local levels where it's really no better than the typical poster children for corrupt countries. Taxis are a completely local (municipal) issue.
However, in better-run and not-so-corrupt societies like Korea, it's not necessary and probably downright harmful.