Fear of punishment

A fear of punishment doesn't fix the problems within reality, or give the confidence to deal with fear, all it does is smother behavior.

Some people think that once they start being nice to their horse, and stop using punishment, their horse will take advantage and go back to bad behavior. This isn't what's happening. If the horse goes back to using unwanted (not bad) behaviors when the threats are gone, its simply because they have been uncovered, and the cause is still there. The behavior was not changed, just hidden.

So fix the problems, build their confidence, and train the behavior you would prefer to see.