OP, your posts resonate with me as I have been in a similar position but on the side of the owner.
Our dog was 12 years old and free to go between the house and the garden all her life, she was always walked on the lead, was very well taken care for, was very well trained, she was my little friend from when I was 12 years old and I couldn't stop talking about how wonderful she was.
Then one day we had builders in the house and one left a door of the house open at a time the garden's door was open and she was gone.
I drove around my neighbourhood and near Ines for weeks, we offered a reward, we put adds in the newspaper and even one in the radio. We got a lot of weirdos calling pretending to have the dog including one that seem to be masturbating while I was trying to make him tell me where the dog was (that's how sick the world is)
Eventually a woman living a fair distance away from us called saying that her brother had brought the dog to the house but was refusing to return her because he thought if the dog had left it was because it was mistreated and despite all the reward ads, he thought we didn't care about her as we were not faster at finding her. The woman called because she could see that it was a very old dog with good manners and nature and she didn't think she would be that if she had been mistreated or neglected.
On pick up the woman told us that her brother noticed her under a bush in a park on the day that she was lost, and brought her home when he realised she was still there 2 days later. I drove by that park several times but being under a bush I didn't see her.
So, although you may find it upsetting that such sweet natured dog's owner is not making a fuss, they care for it. A neglected dog wouldn't trust you to fall sleep near to you and certainly won't sit or rollover, teaching a dog to rollover takes quite a bit of time and dedication and not many people bother with it because it is not a essential skill. Those kids might spend quite a bit of time around him.
So please don't worry for the little dog, he has some owners that have cared well for him.
I now have a RSPCA dog that also lost for a walk and lost her way. I don't know much about the dog apart that she was picked up in a busy area by the dog warden in a dreadful state. But the little thing is the most affectionate dog ever, she is incredibly trusting, it is like having a cheeky teddy bear that is always ready for a cuddle, a game, etc. If it was a rabbit I would tell you she was pretty well tamed as she really seem to enjoy being handled and fussed over.
I'm sure there are some devastated people out there missing her, their only sin being not having her microchipped. Considering the dog's only problem is that she gets violently sick in the car and doesn't enjoy being taken to busy places, I can only imagine that the owners didn't have a car to go and search around for her and were definitively not anywhere near to where the dog was found.