Or maybe someone just loved them and appreciated them for being what they were, productive animals. Some people do love their working animals that way. Back when I was in NYC I knew a horse cab guy who was a cut above the rest in terms of how he treated his "girls" the two horses he used in his daily work.
They ate better than some humans, had a cushy stable all to themselves, and he even alternated days working and/or swapped them out mid day in the heat of summer so they wouldn't have to work a full shift like he did. When one of them got too old and had to be retired he made sure she was given a nice home in the country and good care for the rest of her days. He was a good horseman and those horses were lucky to know him considering how most of them are treated.