
It is because this elephants are trained even when thay are little. Elephants are chained to a big iron ball to prevent the elphant to escape. This feeling of helplessness grows inside the elephant. The animal will try to escape but it will fail due to the weight. The elephant will grow thinking it is uncapable of breaking the chain even though a full grown up elephant could easily break its oppresion. So the elephant is now conditioned not to escape because it has learned he is helpless against its enviroment.