I suspect that even if dogs aren’t obligate scavengers, it often and can happen especially if or when humans defecate in the open (especially if there aren’t any toilets around, let alone good ones at that) and can’t bury their dead well. (that’s without a coffin and gravestone to stop it though not always exactly so). If dogs do devour corpses, it’s often either in the open (they even eat their own owners), in rivers (they do this in India) or dig it up from a badly dug grave.
Keep in mind that open defecation’s still a thing as is burying the dead in inconvenient places and dogs will eat their own owners. The idea of dogs as scavengers of the dead’s even a thing in mythology, especially whenever they’re associated with the dead and underworld. This aspect, as brought up by the Coppingers, influenced old mythology a lot but for some reason gets downplayed in current attitudes. Somebody noted that dogs were even associated with treachery in Ancient Greece before.
This study’s called Shameless: The Canine and Feminine in Ancient Greece. If a dog’s caught dead wandering into neighbours’ premises, killing livestock and game animals alike as well as killing its own owners, then it shouldn’t be much of a stretch as territorial vigilance gives into loyalty. Might the Ancient Greeks be really keen on dogs’ sometimes nefarious tendencies? While this might be the case with only some dogs, let’s not forget that even if the Ancients did have sentimental feelings, it’s neither the norm nor is it consistently practised and believed.
You could own dogs but be sometimes bothered by them and be aware of their baser tendencies. Sometimes some dog owners aren’t that sentimentally close to their own dogs and some people are sentimental towards truly stray dogs. Alas it seems despite reports confirming what the ancients and even some scientists believe, it’s parsimonious to suggest that there’s a big generational divide between the Ancient Greeks and 21st people.
Maybe not always so but still substantial enough to sense a big shift in attitude.