From what you describe, your dog didn't learn that jumping on the couch is bad or wrong. He learned that he can get hurt or that couches have scary things on them. That's lazy. From what you told me you didn't offer any positive reinforcement. You didn't actually train the dog anything other than fear of your couch. You didn't teach the dog to listen to you. I'll stop there because I'm just going off your description and you may have ommitted a lot of things.
Actually, he learned to avoid the traps, and would start sleeping on the couch as soon as we forgot to put the traps out. But, the negative re-enforcement worked -- it was obvious he knew we were displeased if we caught him sleeping there. An invisible deterrent would have worked better - since he couldn't easily check for traps, he would have to avoid the couch completely, or risk being punished.
Positive and negative reinforcement work very well with people. In another life, I was a teacher working with students aged 3 to 60, and by the accounts of others, very good with children. Because of the nature of the job, I had to rely primarily on positive reinforcement.
Negative reinforcement worked very well in the constant presence of positive reinforcement - not much of a punishment is usually needed in order to change a behavior. In most cases, I could simply re-direct a student when they started misbehaving, rather than fighting them over behavior I don't like. If a kid was acting out, changing the lesson up and engaging them worked far better than punishing them. Patience and discipline were best developed through other means. Negative re-enforcement was only used when the student refused to be engaged at all.
Negative reinforcement is used socially. In a polite society, it can be very effective, because it's unexpected. However, when negative reinforcement becomes routine, it becomes abuse rather than a form of discipline - it looses a lot of it's effectiveness, and starts to cause a lot more problems than it resolves.
In a co-operative society, negative reinforcement is almost never needed. When people defect, it becomes required - punishment, but with the reminder that the co-operation will resume as soon as the offender demonstrates better behavior. This is how the legal system works.
Read up on the iterative prisoner's dilemma.