Answer:
Because some species might become invasive and destructive if they escaped.
Step-by-step explanation:
It is correct to regulate which species of plants and animals people are allowed to own in specific environments, to prevent people from entering exotic species that become pests in a different habitat than that which is natural to that species. Putting exotic species together with local species is dangerous and we have many examples of how this practice was once catastrophic.
We can cite as an example the situation that made African snails become a real plague in Brazil. African snails are not animals that existed in Brazil, however, when Brazil was a Portuguese colony, the Portuguese will bring several African snails to Brazil, believing that these snails were used to make escargots. However, the escargĂ´ is made with another kind of snail and when the Portuguese realized it threw the African snails in the wild. These snails reproduced and spread throughout the Brazilian territory spreading diseases and consuming crops.