A nice chunk of the fanbase believe that the Sharpteeth are actually smarter than they are made out to be.
Basically, prey is easier to get in The Mysterious Beyond because of how divided herds are out there, but in The Great Valley, the herds work together to help and protect one another. Any smart sharptooth would rather take the easy route when it comes to getting a meal.
As for Red Claw, I feel that he has a reason to enter The Great Valley that's beyond just getting a meal. What is that? Well, let's just say I have my theories.