In order to keep an elephants behavior under tight control in the close proximity, "hands-on" conditions of circuses, it is necessary for a handler to establish and maintain supremacy. Domination of such a large animal must unavoidably involve elements of cruelty, often including the liberal, constant use of an ankus – a bull-hook euphemistically termed "guide" by those in the business, a whip or an electric prod.
Even if you don't see a bullhook in active use during the show, be sure that the elephant know well the painful consequence of not behaving exactly as the handler want.
Elephants have extraordinary memories and it has been demonstrated that they never forget rough treatment by human handlers. Consequently, they can pose an unpredictable and abiding danger to the public, to their handlers, and thus to themselves.