Not sure what you're asking about with regard to Yellowstone. It's beautiful, you can interact with the animals if you really want to, the rangers will probably arrest you if you try, and you'd have to be insane to try to interact with them anyway. I vaguely remember seeing a story headline in the last couple of weeks where someone got mauled by a bison. When I visited (too long ago), people were walking up to a moose and trying to feed him, but somehow they survived. I got stuck in traffic for a while because a herd of bison decided to walk down the middle of the road; I refrained from reaching out of my car window to pet one of the big ones. Yellowstone is not a Disney movie. The animals have learned that, generally, humans aren't going to hurt them. That just means that they are more likely to approach -- but they'll still attack if they feel threatened, or hungry, or annoyed. So, it's really best not to try to interact with them, because that makes it more likely in the long run that they will end up hurting someone and then being killed as "a problem animal".
Most of the exotic animal "sanctuaries" in the U.S. seem to be more akin to private hoarding operations where someone decides he can give a better home to surplus former pet exotic animals than their previous owners could. See also "rescues".
An author whose books I used to read had a tiger sanctuary in some southern state. I don't exactly doubt that he could provide a nicer home for them than a lot of the people who buy pet tigers, but a cage is a cage even if the food is plentiful. It's not like the tigers could be released into the wild, though.
First of all, I really appreciate your amazing story about sanctuary you've been to, and the Yellow Stone Park in U.S.!!
I am quite shoked there're people who were trying to interact with animals in Yellow Stone, because from what I heared,
Yellow Stone is not like other sanctuaries or animal related cafes.
It's more like wild park for wild animals in order to provide them safe home and
natural environment which is similar to their natural habitat, not for humans to pet them.
And yeap, I think so too. Even if the sanctuary is quite good place for them to live, and it's still better than the zoo or others,
but It's still a gigantic cage, and probably not very comfortable for them to live.
(But even if they could be released to the wild, it's still quite dangerous because of the hunters.)
I hope someday, all wild animals could live in the places more akin to Yellow Stone National Park or safe and natural environments.
And if it's possible, It would be nice that hunting activity becomes illegal in U.S. and in the other countries too.
Anyway, Thank you for your reply and letting me know your valuable experiences!
I'd like to go to national parks or sanctuaries in U.S. or Canada at somepoint.