Why do people have dogs and not exercise them?

The title of this post is a question that I have often asked myself over and over again and still not come up with an answer to. Several years ago my elderly parents acquired a puppy. I don't know why they thought that they could take on a dog that they would never take on a walk. They kept the dog in the house and small backyard until my father passed away. My mother took the dog with her when she moved in with my sister. My sister was no better since they simply kept the dog in the small backyard and rarely let the dog in the house. At the time my sister was complaining that she was trying to lose weight and was on this diet and that. I simply told her to take the dog for a daily walk and she would not need the most effective diet pills she can find but get some exercise and get the dog out of the backyard prison. Well, she never went on those walks and after 9 months of trying to get them to take better care of the dog, my husband and I stepped in and took the dog home with us.  The dog lived on our ranch from the age of 5 years old until she died of old age at the age of 15. She had 10 years of freedom. She roamed our 7+ acres, enjoyed the company of our other animals and had to follow me everyday when I moved the horses from the barn out to pasture. We would go for long walks on county trails.

I enjoyed going for walks and exercising our dogs, so I still ask myself, why would anyone own a dog and not even think to walk them?