A lot of people don't understand the importance of pet and sport dogs to the supply and training of working dogs with serious jobs.
The protection sports (IGP, Mondioring etc) are an important seedbed for new ideas for how to train police, military, anti-poaching etc dogs. The people who work the dogs don't have the time or (often) the expertise to tinker about with training techniques, but the bods who are serious about the sports do. They want to win, if only to prove their own training, and dogs are their entire life (they often fund their sport by breeding and training dogs). Because they want to win, they are highly motivated to find the best ways of training the dogs. Some of the sports demand that the dog has a positive and energetic attitude, so keeping the dog happy while being under control is part of it.
I suspect the same is true of eg spaniels used for drug detection and similar. Without the enormous pool of working gundogs to dip into, government agencies would be hard pressed to maintain a suitably diverse and healthy gene pool to provide the dogs they need.
And without the pet market to find homes for dogs who don't quite make the grade as gundogs, what would happen? I've got one as a pet who is unlikely ever to work because her personality is just not suited to it, despite her breeding. I give her the outlet she needs, but I can't work her, though I work my other dog.