I have always said there is really no such thing as a bad dog – bad behaviour in dogs is the product of bad owners or human behaviour or neglect. It’s my animal welfare streak coming out sorry. I don’t think that the dog deserves any punishment, its barking is instinctive and because of its surroundings and threats it perceives. It’s owners’ choice of dwelling is inappropriate for it so it seems, but that is not the dog’s fault. Bark collars are painful and cruel and banned in many states and territories in Australia (see https://kb.rspca.org.au/knowledge-base/is-the-use-of-electronic-dog-collars-legal/). Training is a possible answer – how this can be compelled I am not 100% sure as I’m no legal expert – however it is up to the owner to get off their backside and do it already. Training clubs near me are $2 per week for an hour, it is not expensive. I feel for you, I really do, but bark collars and treatments like that are simply cruel. Focus your energy on the owners, and please not to punish the dog.