^^^
I am *assuming* that was taken at a zoo?!!!
It depends on what you call a zoo.
In the U.S.A., game animals for the most part are considered to belong to the State. In South Africa, where the photo was taken, as long as the landowner has the area fenced in, the animals within the enclosure are his. Some game farms or reserves are fairly small, small being 4,000 to 5,000 acres and some are large, i.e., 85,000 acres or more. And yes, they do put fences around the 85,000 acre ones.
The photo was taken on a smaller game far; maybe 8,000 acres as I recall. Though the guy is petting it, make no mistake, they are dangerous and I would never have wanted to be around them on foot without a gun. The ones aclimatized to human contact are actually more dangerous than the wild ones. I was told that not long before this photo was taken, one of the trackers was chased around the bakkie by one but escaped unscathed.
If I were ever to hunt Cape Buffalo, I probably wouldn't hunt one on a game farm in South Africa. I would prefer mine wild.
There are some species that can be hunted free range in South Africa. I hunted Cape Grysbuck in some unfenced vinyards in South Africa. Also some species like Baboon, Bushpig, Jackal, Warthog, Caracal, etc. go pretty much where they like so even with a high fence, hunting them is essentially free range. Also other species even where there are no fences don't migrate a lot so if on a large game farm, hunting them is essentially free range.