Well, I'm only coming at this from my perspective. There are other things that my parents did that I didn't do. I didn't make them eat food they hated or eat everything on their plate (small stomachs); I didn't demand all A's, I didn't load them up with chores, and I didn't force them to babysit when they were 10.
As I said, I only spanked them a couple of times, and they were young and impressionable. Their clothes were on and it was a couple of swats with my hand and not done in anger. It was mainly to impress upon them that they have to listen. Apparently it was enough.
How many times did you tell your kids not to talk with their mouths full? Or chew with their mouths open? Or not to answer the door when you were in the bathroom? 1,000,000, I bet
They sometimes don't listen! You have to repeat, repeat, repeat! And when it comes to answering the door when they don't know who's on the other side, or running off to God knows where after school and not letting you know, or dashing out in to the street... it's a safety thing. You can tell them a million times, it still happens. A swat on the bum, combined with loss of privileges, goes a long way, quicker. You can talk until you're blue in the face, and some kids just don't listen.
I don't personally give a crap about Sweden's graphs vs USA or anybody else's. I've finished raising my kids and I'm happy with them. I'm a lot more lenient than my parents, but then... I only had 2 kids and they had 7 (in 8 yrs!), and things were different then. Also, I didn't repeat the things they did that I hated. I never put soap in my kids' mouths and I didn't use a hairbrush or wooden spoon on bare butts, etc, etc. There was a lot more interaction, debate, and family activities. Again, I only had 2, which I think makes a difference.