The difference is that elephants can be very dangerous and can`t be cared for nor handled by just anyone. If you hire someone who has no experience and no training to care for an elephant, you can`t be surprised that the elephant is left in chains 24/7. In this situation the owner is actuallly the one who is mainly responsible and not the poor bloke who is terrified and scared and has no idea how to safely do what he is asked.