What makes you think someone using smacking as punishment for a child has lost their temper? I don’t think it’s always the case, bizarre though that seems.
It used to be absolutely routine as a correctional technique and a friend’s husband sometimes smacked their children when he got home, for example. No temper involved. She once told me the children had the choice of corporal punishment or grounding and they chose the former, to get it over with. My own children were not smacked, but experienced psychological pain delivered by their father, which I think was just as damaging.
I also know my mother hated smacking me, but did it when I was very young, I think on the grounds that pain is a good deterrent and it was just normal.
Doesn’t make it right, but I can see a difference between domestic violence against a wife or child and a controlled smack to a child who is too young to understand reason as a method of discipline.
It’s better that the latter is banned as the line between the two is too easily blurred, but my mother was not the same as a man beating his wife, just because it is now considered unacceptable to do either.