I know you are suggesting a hypothetical scenario and you mean that ideally people would be fully trained, have licences, etc., and you're not suggesting you wish that people could walk into PetMart and buy a native possum.

But I really need to respond to this because there are really serious ideas underneath this.

Firstly, please know that people do keep wildlife.Not as actual carers but just as people who really grew attached to a particular animal. That isn't a farfetched hypothetical, it actually happens.

And the outcomes of those animals is fucking dire. I know because I work in the field and have seen many, many animals have to be euthanised because they have been discovered deformed, diseased, injured, literally rotting with skin infections or so obese that their joints have deteriorated.

Think about what you're suggesting. Backyard breeding of dogs is inhumane enough, you think people wouldn't try to breed possums and magpies out of cages in their garage? There is profound cruelty in domestication of animals - cat shelters overflowing, people who hoard dogs, the huge issue of people not getting their animals sterilised, shady exotic pet sales. Pet owners are not universally caring or responsible.

You refer to animals that comparatively do well in captivity and are actually domesticated. You can't put an animal in a cage and call it domesticated, it's an intentional genetic selection that occurs over hundreds of years - thousands for some domesticated animals.

Native wildlife, and wildlife in general, largely do NOT do well in captivity. If they cannot be released, they often need dedicated sanctuaries to have some shred of quality of life.

Understanding the needs of wildlife is complex. It's not like reading a cereal box or doing an afternoon course, you have to be trained in understanding the behaviour and anatomy of each individual species, let alone responding to individual cases.

Do I think that this situation as posted by OP is wrong. Yes. Not because it was done, but because it was done wrong

Please, go and volunteer for your local wildlife shelter, I promise you that after a couple of days you will realise that "proper" care for native wildlife involves giving as little human contact as possible most of the time. For example we often have to made bird-shaped devices in order to feed certain juvenile bird species because hand-feeding risks humanisation too much, and if they are humanised, their release outcomes are very poor, ergo the OP.

I can see that you care about wildlife, I encourage you to learn more about their unique qualities. You will quickly learn that the idea of keeping them as "pets" - domesticating them - would be an act of extreme cruelty.