Horses don’t care about being straight and balanced. No horse spends time worrying about how it could be straighter and move with more balance. They don’t even know they are crooked and there is a better way.
The next time you get frustrated because your horse keeps falling in on a circle or insists on moving with its head up or hops into the trot, ask yourself what will it take to make the new way of moving feel more comfortable than the old way?
The student wanted to know why. After all, if it is physically easier for a horse to travel in a balanced way, why would they choose to circle out of balance? That seems a logical question to ask.