Compliance fear - doctors are afraid people won't do anything if the changes are too drastic. Peer review fear - doctors don't wish to practice differently from their colleagues. Expectations - patients expect doctors to perform procedures, but successful prevention means no procedures performed. Lack of nutrition education - most physicians receive less than 3 hours of nutrition training during medical school. Real doctors don't talk about food.
Patients generate profit.
The healthiest, longest-lived people on earth have no access to modern medicine. They practice prevention. Profound social changes will occur when it's no longer considered normal to die young. The medical profession, pesticide industry, cattle ranchers and general public all share the same philosophical aspirations for a better world. There is, however, disagreement over the best way to get there.