I believe that views of child abuse has changed over the years. It seems that over time child abuse has become of a issue that is discussed. Before, it was issue that was private and left to the family and was considered no one else's business. There are agencies that exist now days, such as child and family protective services, that are dedicated to stopping child abuse. These kinds of agencies did not exist before.
As far as physical abuse is concerned, the definition has changed over time. I distinctly remember as a child, if I were to talk back, do something bad or dangerous, I would get a spank on the bottom. It was never with a spoon or anything, but the hand of my dad. It got my attention and I knew never to do whatever I did or said again. I do not consider that abuse by ANY means as my parents gave me a rationale for why they did it, and didn't do it often. I think I turned out pretty good in all honesty. Who knows where I would be if I didn't have discipline. Ask your Grandmother how she was disciplined. I bet she has probably had "a switch taken to [her] backside" when she was younger. Today if you grab your kid by the hand and yank him/her out of the middle of a street when a car is coming and they ran out there and you dislocate his/her shoulder, your parental rights are suspended so quick. Nowadays you glare at your kid when he/she makes a smart remark, you probably have scarred that child for life and someone is calling DCFS on you before you blink. There is a difference between abuse and discipline but everyone has a different definition and it will always change over time.
Child abuse is not a recent phenomenon. The main change over the last hundred or so years has been in public attitudes toward the problem. Until fairly recently (in an historic sense),children have been seen as extensions of, and "property" of, their parents. When child abuse was known to be happening, the attitude was more one of letting families deal with their own issues. When children's rights began to be recognized in a legal sense, societies began to take more of an active role in their protection.
Before the Child Labor Laws that came out after the early 1900's, children were born into a family in America for work. The fact that many immigrant families had to use every family member in order to "make it" in America, allowed the business/factory system to allow childern to work long hours in dangerous environments. After the Child Labor laws, the ideal of child labor changed since it became illegal to have childern work in those environments and under such harsh conditions. The Child Labor laws were really the catalyst for a change of viewpoint on how families treat their children.
it used to not really happen until people learned that they were capable of it