I think Flanuva is correct, but it also depends on the animal. If it's a species know to be a more common carrier of diseases, then they don't want to run the risk of introducing an illness into an area that might not have it.
I have read in the news of a bear cub that was distroyed after they confiscated hit and a 9 year old buck was caonfiscated and was beening returned to the wild. You think after 9 years this animal has no fear of hunams or other things (dogs), Do you think that animal can adapt to the wild and survive?
I would think a bear raised by people would be more dangerous to the public released, than a buck (who will just get shot quickly and tagged). Though I do remeber reading about a PA buck that gored someone during rut, raised by humans.