In the US, there is a gray legality when it comes to the limits parents can discipline their children and it chages state-to-state since children are their parents property until adulthood. What is considered "reasonable" also heavily depends on the judge and jury.
As for my own experiance growing up in Asia, in-family abuse was a common practice. But I'm sure the number has decreased. The main difference is that it wasn't considered abuse; it was consisted discipline. Children receiving harsh physical punishment from their parents being considered abuse mostly streams from the west. There's a lot more I can say about the west's influence on the east in recent years when it comes to idealogies but I have to go to work soon. Just note that South Korea gets influenced by the US a lot more than other eastern counties.
i thought cases of in-family abuse are seriosly condemned in western countries? eh, not so much in asian countries I guess...