A doctor is a doctor, a nurse is a nurse, and a respiratory therapist is a respiratory therapist. In the same way we can say a dad is a dad, a mom a mom, a child a child, a teen a teen, and a newborn a newborn. You cannot expect one to comprehend the world as the other as each has a limited scope of wisdom from experience and observation.
You cannot expect a child to understand the hypoxic drive theory even if there was an interesting book on the subject. You cannot expect a newborn to babysit a child, but you can expect that a teen can do it. An adult can do it, but not another child.
In the same way, you cannot expect the doctor to be as good at nursing a patient than a nurse. You cannot expect a respiratory therapist to be good at changing diapers any more than a physician would be good at it. Surely a respiratory therapist can start IVs, but he won't be as good as a nurse.
Each person has abilities based on empirical data obtained during the course of life; based on our experience; observation; education. It is for this reason we must, as a medical industry, allow folks of each profession to perform the duties they are trained in. Nurses do nurse duties to the best of their ability, doctors do doctors, and RTs do RTs.
Now surely a physicist can write a poem, and a poet can do physics. Yet never will the poet be as good of a physicist as the physicist. And never will the physicist write as good of poetry as the poet. Surely there are rare feats, but good poets are rare as good physicists are rare. Yet good poets are even more rare than good physicists.
So my point is that we must do what we are best at and let the people who are best at something else do it to the best of their ability. In this way we make better progress. If, hence, the doctor changes the diaper of a 90 year old patient, he may make a bigger mess of it. I know if I did the same I wouldn't be so good. A nurse, however, and the nurses assistant are so trained.
This is why I believe physicians, however brilliant in what they are, do not know respiratory therapy. It is, as Egan noted, beyond the scope of a physicians knowledge. It is, however, in the scope of the RT's wisdom. RTs know RT. RTs therefore should be allowed to do RT without the physician stepping on his shoes. RTs should be given more autonomy in order to benefit the patient.