Some people shouldn't be allowed to own a pet, and yet these bad owners keep adopting pets and abandoning them when caring for the animal becomes "too hard".
Rhino Lightning the Boxer fell victim to one of these bad owners when he was adopted from the Humane Society then returned months later because "They felt that he was a little too rambunctious with their small children".
But one of the kids clearly loved spending time with poor Rhino, and the helpful letter she sent along with Rhino shows she's going to be a great pet owner- unlike her parents.
Her adorable note contains advice like "Rhino need's lots of atenchen", "don't tease him with treats he will start to bark like crazy" and "his full name is Rhino litning then your last name. please don't rename him".
Rhino was adopted soon after being returned to the Humane Society of Utah, and the new owners agreed to follow the little girl's advice and let Rhino Lightning keep his awesome name.
Read Dog Is Returned To Shelter With With A Letter From The Girl Who Loves Him here
I think your attitude in this situation is actually damaging and can potentially cause harm by pushing an unrealistic view of how rescuing animals can work. The first week or two can tell you a lot about an animal, but people need to be prepared for changes or difficulty on longer timescales. Chiding people that may have been trying very hard to do the right thing isn't helping anyone, unless the goal was to just find someone to call an idiot online for no particular reason.
And return policies with shelters is always been a important thing to discuss when adopting, because it can sometimes take quite a while to figure out how the pet will behave. I've seen animals that take a couple months to settle in enough to show their normal behavior, at which point it can take a couple more months to see how trainable/malleable that behavior is. Outside of more definitive cases, it is very easy to spend 6 or more months before finding out that your newest pet is not going to be compatible with kids or other pets. It is also easy for the shelter to not be able to foresee this without taking care of the animal in an actual home environment for some time (... e.g. fostering it for a couple months).
I don't think there is enough info in the story to say what type of pet owners they were. You can't tell if they neglected and ignored the dog or spent that time unsuccessfully trying to socialize and train it.