But let's go with your incorrect assertion that it doesn't cause harm. Try slapping one of your co-workers, and then in court saying "but it was a completely non-injurious form of discipline" and see how far you get.
All that said, yes there is a difference between parenting and abuse. However, children are not tiny adults. They are tiny humans. You can often tell how they are feeling or why they are feeling that way, but it isn't by thinking the way a well-adjusted adult would. The whole point of parenting is to help them get to that point eventually.
If someone acts the same way at 25 that he acts at 13, that person would be a sociopath. But 13-year-olds are rarely sociopaths (i.e., they are only when truly mentally ill).
Children can't function the same way adults do, and we can't treat them the same way, full stop.
This is the kind of willful obtuseness the poster upthread is talking about.
I'm just saying that hitting a child is always as abusive as hitting an adult, and often more so because the child has no chance of escape.
There are many ways of parenting, and msot of them do not include violence against the child.
This is why hitting children is illegal in many countries.
Never mind treating children as adults: how about we treat them as humans, with rights that need to be protected?
And that's pretty much the key point. You cannot pretend children are adults.
Also, this is why you should be a patriot and subscribe to Science rather than Nature.
What definition of violence are you using which doesn't include hitting children?