I've seen doctors that:
1. Immediately said 'Cancer' to stomach issues on an old person. They just didn't care, another doctor resolved that.
2. Eye doctors that would not investigate anything and just prescribe eye glasses and would recommend local companies that they owned or had a stake in.
3. Fake gynecologists that did C-Sections brutally without any experience
4. Fake plastic surgeons with no experience just going by word of mouth taking rich peoples money
5. Fertility doctors doing human egg-trafficking.
6. General doctors forcing appendectomy if under-18s came to the hospital with any stomach complains (they could not refuse, doctor got money for the surgery)
Sure, human body is complex. That wasn't my point.
Where I'm from half of these points mean actual jail time for the physician attempting them, most of the rest (like kickbacks) result in standing in front of an ethics committee.