While I understand where you are coming from I have to disagree with your generalization.
We only take in rescued dogs. With one exception we have never had a puppy that we could train from young.
Many people like us rescue dogs, and some focus on rescuing and fostering very old dogs to give them some enjoyment in their later days.
Many of these rescues have had tough lives, with no or minimum training. Our current rescue, who we have had since May, was two when we got her. She had previously been kept out back in an unfenced yard downtown Jacksonville and allowed to roam.
It takes a long long time to train a non-puppy rescue, and some of the older ones will never be trained to where they should be.
So I would be careful when you see a badly trained dog, it may not necessarily be the current owner's "fault."
As for shock collars, not in this house.