From woofgang's middle link "Why won't dominance die?"
"The domestic dog is a neotonised version of the wolf-type ancestor, a specialised variant that evolved into a newly formed environmental niche to scavenge the domestic waste of human settlements."
I was looking for the term neotony and glad to see it in this article.
Supposedly, adult wolves almost never bark; it is an activity restricted to puppies, with them.
We've bred dogs to have more and more puppy-like behaviour attributes and yapping dogs are an unfortunate side effect of this, I reckon. Lonely, needy, owner away at work, so they yap all day. Owner gets home and they are sweetness and light because they have company again. *Owners do not know there is a problem going on, behind their back*.
Use the voice recorder on your phone and, after a visit or two to just get aquainted, maybe broach the subject and make it clear that you're playing the tape to them merely as information, not accusation. You could even say that you were concerned about the animal's welfare or that you thought it was trying to get bystanders to help with some crisis, involving them, indoors.
People who leave dogs in "home alone" situations make me want dog licences to make a comeback.