If all insurance companies published all the code combinations covered for every procedure/diagnosis, I might buy this argument. But they don't. I've asked Blue Cross and they said they don't disclose those details. Many billing codes are open to some interpretation. So if insurance companies aren't transparent about what codes are or are not covered, why are the doctors' offices at fault when something is denied? Why isn't the default response from every insurer "code X isn't covered in combination with code Y. <some clarifying questions, explanation, and related codes>"? Why is it a black box?