Some dogs are non responsive, while others just seem depressed. In many cases the dog has developed this way either from a series of negative experiences during development, or it is in a poisonous household and they just shuts down emotionally. To help owners understand some of the difficulties and frustrations they are having and why. There are numerous books and seminars you can attend if you really want to know more. The owner work takes much more time and energy.
Most owners have unrealistic expectations of dog training.
They think it is going to be easy. Reality is that this is what I do and have done every day for 16 years. What I am not good at is golf, piano, computer programming, or whatever your profession or hobby may be. Dog training is like going to school all over again. All those frustrations of learning a new skill surface.