Plains Indians who rode and hunted from horseback used a rawhide thong around the lower jaw of the horse. That and leg pressure told the horse which direction to turn.

American Western (cowboy) horses are trained to neck rein -- the feel of the reins on their neck and pressure from the opposite leg of the rider indicates which direction the horse should turn, not pressure on the bit. While a cutting horse is working separating on steer from the herd (or similar work), the rider is mostly just along for the ride. The horse is trained so well, it doesn't need direction from the rider.

Only and inexperienced rider would jerk a horse's mouth around and most bits are there, ultimately for control, but usually due to training, not that much is needed.

A bit in itself is not cruel or even uncomfortable.

Just my 2 cents worth...

Linn