LEO and Mil working dogs are trained to be aggressive...as we all know. And they spend a lot of time leashed or caged up or kenneled when they're not actually working. I think this makes them unhappy. I think if K9s spent downtime with their handlers in addition to duty time, the bond might be stronger.
My Belgian Malinois is not motivated by treats, he's motivated by work, by doing things with me. He wants to run, herd, ride beside me or be with me or the Mrs all the time. He loves his family. Maybe working dogs are missing that family involvement.