That the same patents would not be granted for clothing in that vague of terms, that's what. They'd require degrees of curvature, lengths, materials, etc.
Actually they are, they are called ornamental patterns. Just like the patent Apple got on the iPhone.
If what you stated was true, why aren't call the car manufacturers copying each other? Ford has a very distinctive look, I can only imagine if Toyota released a model that looked just the F-150, they would be sued quickly.