Anyone that think shock collars are cruel, in my opinion, have no experience of using one. Yes, they can be used for cruelty in the wrong hands, but they are generally used to condition the dog to respond to extremely low stimulus, as in lowest perceived level. They would only be used to 'shock' the dog in a life or death situation, and in proportion to the dogs energy levels for the shortest time possible. Would you rather a dead ewe than a dog getting a nip in the neck? A lot of good dogs will lose their lives in the wake of this. It's sad.
A bat, a foot, a rock, a rope can all be used for cruelty, we wouldn't ban all these.