You look at a herd of cattle and well, they all look the same. . . but they know. They all have an individual personality, and those personalities change from day to day. They can have their grumpy days and their happy days and their serene days. But it's unpredictable. You can't be off in outer space when you're dealing with animals.
It's true that charisma can make a person stand out for a moment, but character sets a person apart for a lifetime.