Keep in mind the opinions of the people who are "sticking up" for people in my profession do not necessarily share the same views of those in said profession, and in this case probably have nearly opposite views on most matters. Quite frankly, if an owner of a restaurant ever confronted a guest about how much they tipped, I'd find a new restaurant to work at, since we wouldn't exactly be looking out for the guest's benefit. (I only complain about tips behind closed doors, not to the guest's face )

Chris