...Kids can tell if they were punished because they did wrong, or because you were just pissed. When kids get punished because parents are annoyed, they don't learn any positive lesson from it. When they get punished because they did wrong, they learn.
If your emotional state has more to do with your own annoyance at your child having inconvenienced you, then your child picks up on that and is more likely not to reflect on what they did wrong. However, if your emotional state is calm and loving, yet reflects a high standard for your child's behavior, then they are more likely to be able to reflect on what they did wrong, rather than just being pissed off that you are pissed off.
Free market capitalism isn't right for America because it works better. It's right because it's free (and it works better).