As of 2020, even after so many medical and governmental organizations have endorsed plant-based guidelines, why don't doctors recommend WFPB to their patients? A paper published in Kaiser Permanente explains the dynamics lucidly:

Publication: Is There a Lack of Support for Whole-Food, Plant-Based Diets in the Medical Community? by Maximilian Andreas Storz, MD, The Permanente Journal, Vol 23, No 1

My understanding of the three points in this publication:

(1) Doctors don't get paid to give nutrition advice to patients: doctors walk on an economic treadmill characterized by "diagnose & treat (with medicines & procedures)", with as few minutes spent per patient as possible; this maximizes profits for organizations that employ them. Nutrition advice & coaching can't be given in 10-15 mins; it requires hours & hours of education & is not as profitable. A medical doc who comes in touch with WFPB guidelines faces an ethical dilemma: "What exactly is my profession about? Should I be teaching people WFPB guidelines instead of practicing medicine as I was taught in medical school? Would that mean that I will make less money than what I make today?" In fact, the entire medical community faces this question as a collective: if 60% to 70% of chronic conditions can be prevented (and even reversed to a large degree) by simply adopting healthy lifestyle habits, what do we need so many medical doctors for? One of the main reasons is that most doctors aren't even familiar with these guidelines! Why?

(2) Lack of nutrition education as part of medical training: The vast majority of doctors are not educated in nutrition. They themselves fall sick to the same diseases. And they don't actually know that we can treat the vast majority of modern chronic lifestyle conditions through lifestyle changes alone! Check out Personal Stories of 20+ Whole Food Plant-Based doctors: not a single doctor in these stories learnt about WFPB as part of their medical training. They came in touch with WFPB via ForksOverKnives documentary, or through Google searches, or through patients' who experienced remarkable results through adoption of plant-based diet, or through chance contact with medical literature on WFPB. None of these doctors learnt about the profound relationship between food and disease in medical school. Today, ACLM (American College of Lifestyle Medicine) has come into being to help awaken doctors of this amazing approach to treating medical conditions but their outreach is still limited. The emphasis in medical school is treatment with with pharmacology (drugs) and invasive procedures. The idea that a serious disease could be prevented or cured by making changes to our food choices is rarely taught in medical schools.

(3) Patients expect quick results with pills and procedures: Patients are not attuned to the idea of making lifestyle changes to possibly reverse serious medical conditions. Soap operas, hospital movies and pharmaceutical ads make patients believe that the only way to treat chronic conditions is through medicines & procedures; the idea that simply changing our food habits could help us reverse a serious medical condition is met with incredulity: "Really? I came to you to figure out what to do about my chest pain and my diabetes[ and you're asking me to give up meat, fish, eggs, dairy, processed foods, oils & sugars? What are you talking about? You must be kidding, doc!"