Working dogs, and I’m referring to the police service breeds, have very high prey drive. They will do just about anything for a toy, and don’t even perceive danger when in prey drive for a toy.
Thus, harsh methods can be used on these dogs in ways that you could never do to a pet dog. That doesn’t mean these working dogs are immune to the stress side effects, but it is easier to mask for the spectators.
Have you ever watched a magician? They do this and that trick, and it is designed to fool your perceptions. They can mask what is really going on. That is what can be done with a service breed.
If a method is valid, it should work with all dogs and not result in a psychologically or physically damaged dog. Lower drive pet dogs do the same tasks, but without the same amount of zoom. Push them too hard and they shut down in one way or another. In my opinion, it is a good idea to first learn to work with pet dogs and then build up to working dogs. Then you can see the stress side effects of what happens, and you will better perceive these same effects even if they are mostly masked by the working dog’s drives. In the end, the working dogs will work better, without the conflict and without the stress and resulting displacement behaviors.
Plan accordingly.