True.

I suppose in these (and many) cases, it's simply that this feature is turned off; probably regarded as a bug by the user.

Or this feature simply does not exist, contrary to your belief.

Well, if you think that Balko mis-reported, go ahead and ask him for clarification.

No, I don't think so. I don't see where he said dogs are trained like that. He actually said almost the opposite - dogs are not ignoring weak smells.

I'm not following. He said that 1) such training is possible, and that 2) at least in some cases, it is ignored or that dogs who have this capability are rejected.

So indeed, the feature appears, at least according to his source, to be available. And it also appears to be regarded as (or mistaken for) a bug by the users.

I see. It seems you have your own meaning for the word "feature" that makes it interchangeable with the word "option".