It looks as though this discussion is revolving around the semantics of the word "work" A definition of the word is held to be:
"exert oneself by doing mental or physical activity for a purpose or out of necessity"
Regardless of my own personal "work ethic" which might determine how much exertion justifies the term "work", by the above definition, Obedience / tracking / agility / stock / security, hell even show dogs trained to perform at their peak in the ring are working when they are being trained and when doing what they have been trained to do. Regardless of how much fun it was to do it.
The reverse argument could easily apply, is a stock dog working when it is acting out of instinct?
Phill