People can be a-holes when it comes to animals. But thankfully there are many who try to save animals as well.
I'm one that rescues dogs (PitBulls) from bad situations.
"Line of duty" is our creation, dogs shouldn't be part of that. They don't have any duty, especially towards us.
You named the word "job". What job? What those dogs get for doing their "job"? Food? Cuddles? There's plenty of well paid personnel among Police and Military. Let them do the dirty work if they want. They have a choice, a dog doesn't.
About the "working dog" theory, it's exactly the same. We created that, exploiting dogs (and other animals) for our own profit, for centuries. In nature, a "working dog" never existed and never will. Do you really think it's ok to decide which "work" a dog must do? Again, what's the reward? The reward goes to US, not them. That's not a job, that's exploitation.
We should not be using dogs to do dangerous military/police duties, I think that's wrong ... I don't agree with many military/police tactics.
Agree, "line of duty" is a human creation that we thought up for ourselves and our companion animals, and in the case of most animals it was not their choice to be our companions.
On the other hand,
the domestic dog was created by wild canines that decided it was to their benefit to become partners with humans so they could get easy food and shelter. They made that decision, not us...and that was 40,000 years ago.
We have since created many tasks that we want them to do with us and/or for us in this ongoing relationship, because humans exploit the whole earth.
We set the terms of our partnership, we decided we would take care of them if they help us with things that we do for survival, and they do most of those tasks willingly.
Dogs naturally alert for danger, it is the first thing that we benefitted from.
Dogs hunt in a group, and they help us do that, the second thing that we benefitted from.
In recent times (last couple thousand years) we have thought up lots and lots of additional tasks.
Dogs love doing nose-work, it's a job they enjoy.
Bird dogs love to retrieve prey.
Great Pyrenees love their goat companions and protect them very willingly, they don't like to sleep indoors with the humans, they want to be with their goat brothers and sisters.
Herding breeds love what they do.
Terriers love to hunt and kill vermin, they need little to no encouragement.
Many domestic dogs are very naturally protective of their family/pack...the same way wild canines are, so guard dogs are doing what they naturally do.