Animals do not talk because it does not do them any good. Talking requires a brain that can control the vocal cords finely, and not many animals have that kind of brain. Only some parrots, some songbirds, and humans are capable of doing that. Not even our closest relatives, such as the great apes, have that kind of brain. Additionally, even human infants are incapable of talking until they are about 18 months old. At that age, the vocal cords have moved to their position found in adults. Human infants are born with vocal cords in the same position as apes. The migration of the vocal cords coincides with the development the brain. Before 18 months of age, human infants do not show a preference for either the left or right hand, but they do show that preference when they start to talk. If they are right handed their left brain controls speech, and if they become left handed their right brain controls speech. Curiously, parrots that can talk are predominantly left-footed and they control speech with their right brain.
Additionally, the FOXP2 gene of humans show a difference of 2 amino acids from the chimp version, suggesting that these 2 differences have something to do with the evolution of speech, because humans who have a defective copy of the FOXP2 gene have speech disabilities. As one can see, it took a lot of different changes in humans (relocation of the vocal cords, mutation in the FOXP2 geen, and the ability to control the vocal cords finely) for us to be able to speak. For other animals, they can get by without speaking and they can get by without a brain as complex as ours. Therefore there simply is no need for them to talk. If there is no need, there is little chance that what is needed to speak will even evolve.