Petkeeping vs. Zoos

What is the distinction between petkeeping and zoos? Zoos are morally questionable because they keep animals in a confined space for the purpose of entertaining humans. Petkeeping, like zoos, takes animals out of their natural habitat and keeps them in a confined space for human use. In both zoos and households with pets, the animals are usually cared for, and sometimes cared for well and loved. Other times, animal are abused. In both cases, the animal's welfare is in the hands of humans. Sometimes this is a good thing; sometimes it isn't. Many people argue that petkeeping is morally acceptable because they have given their pet a loving home, and without them, their pet would have no place to go. Similarly, some zoo animals may have been saved from dangerous situations and given a better life in a zoo. However, this doesn't address the issue of petkeeping or zoos as an institution. There are good and bad cases that come out of these institutions, but it doesn't mean that we can decide whether or not they are problematic based on these cases. Some marriages are loving, happy unions, and some are abusive and traumatic. We cannot critique the institution of marriage based on these cases, because there is so much variety in peoples' experiences. To evaluate the moral implications of petkeeping (and zoos), we must not focus on specific cases (both good and bad), but the suggestions zoos and petkeeping as institutions make about our relationships with animals. Perhaps petkeeping is seen as morally acceptable more often than zoos are because people have bonds with their pets that they are too scared too question. Since I am a person who has never had a pet or had an attachment to an animal, it is possible that I and people like me can look at the issue of petkeeping more objectively. It is also arguable that since I have never had a pet, I don't know what I'm talking about. Still, I can't help but see a similarity between the practice of keeping domesticated pets in your home and keeping pets at a zoo. What, if any, are the moral distinctions between these two practices?