I've never spanked my kids, not even for the common reasons given by many parents. When my kids showed interest in the electrical outlets, I would gently pull their hands away and show them that outlets were made only for plugs. We would walk around the house to see the outlets and I would show them how the only thing that was ever in them were cords. They grasped the idea immediately.
When my son at age 2 let go of my hand and started to run through a busy parking lot, I reached out and grabbed him by the shirt and pulled him back to me. I didn't spank him. Instead, I firmly held his hand as we crossed to a safe spot, then I got to his level and told him very simply that he has to always walk and hold my hand in parking lots. In nearly three years, he has not repeated his mistake. I think that parents who spank are often underestimating their child's intelligence. In both of those common cases, spanking was completely unnecessary, yet if I had spanked I probably would have given that credit for their change in behavior.
There is never any reason to hit a kid. There is always an alternative. Sometimes the parent might have to think a moment to know what it is, but it is there. Besides, most of the reason parents spank kids is because they know they can. How many of us would follow the jerk who cuts us off in traffic, causing us to slam our brakes and almost wreck, if punching him in his face were legal? Yet, it's not legal, so the vast majority of people just swallow their anger and move on. In my opinion, an adult nearly causing a collision in a car wreck is much worse than a young child drawing on the walls or accidently breaking a vase. Yet the child is much more likely to be the one physically disciplined simply because it is acceptable in our society. Well, society is made up of people, and sometimes people are wrong.