3yo thinks everything is a joke

So, my soon to be 4yo thinks everything is a joke. Can’t take anything seriously. When we want to reprimand him for disobeying us, he just laughs at us. Is it normal behavior at his age or am I too soft? Is he immature for his age? Should we be using punishment more?

FYI, we don’t use spanking, however I feel I am a fair, yet firm and decisive parent. Just wish there was a way to make him acknowledge the seriousness of some things - eg. Running away in a parking lot, hitting, running around the house when we should be getting ready, etc.