You can see oi zuki in many styles of martial arts. It is very common in various traditional martial arts. But it can also be seen in boxing, MMA, and even in back yard brawls. You just need to look for it.
The karate oi zuki examples are mostly basic versions and not what would be used in actual combat. The karate oi zuki competition example is not oi zuki. And the one with the little kid is not your common karate oi zuki at all.
