You mentioned negligence higher up. Lets talk about negligence and talk about bad doctors. Physicians are human and humans will always make mistakes. There is absolutely no alternative it will happen to every physician. Some mistakes are very minor while others may have catastrophic results. A physician who made a mistake is not necessarily a bad physician, they may have made a choice on treatment options, that choice was not the best option and unfortunately a patient suffers the consequence.
Yeah, no. Some doctors are worse or more careless than others, and the threat of malpractice suits gives them a massive financial incentive to get better at their jobs, whether through continuing education, creating protocols to prevent certain mistakes and problems, or what have you. For that incentive to exist, negligence has to be the standard.
Sometimes medical negligence is leaving a surgical instrument or roll of gauze inside a patient's body. That IS a bad doctor, because part of being a good doctor is having protocols in place (or following the ones your hospital put in place) to prevent stupid mistakes like that from happening. Sometimes negligence is neglecting to wash your hands, change your gloves between patients, etc. If malicious intent is the standard, then a patient left with a sponge or tool inside him after surgery has no recourse: he has to pay for corrective surgery himself, he has to eat the cost of taking time off work, and he has to suffer (the pain caused by the original negligence plus the pain of the extra surgery) for nothing. None of that gets any compensation unless negligence is the standard. Similarly, if hospitals couldn't get sued for spreading infections through bad hygiene practices, that would basically be a license to be careless--in fact it would be a license to get paid MORE for being careless, since patients who get infections need more medical care as a result.
I will give you a very common example: A patient sees their doctor with belly pain. The doctor evaluates the patient, gets labs, and treats the pain. The patient feels better and goes home. The doctor chose not to get the CT scan since that imaging carries is a high radiation dose and comes with its own risk. The patient goes home and turns out the physician missed an appendicitis which ruptures. The patient has a bad outcome requiring surgery and extensive in-hospital stay. Is this negligence? I don't think so. It is a bad outcome though in many states this is a lawsuit that the patient will win.
The reason the patient will win is because in your example, the doctor actually was negligent. What you're describing isn't the standard of care. The doctor should have palpated the patient's belly to see if there was pain in the area of the appendix, should have done blood tests that check whether the patient was fighting an infection, and if the tests were positive the physician should have followed up with an ultrasound. A CT can diagnose appendicitis but an ultrasound can too, with no radiation and at a far lower cost. If the patient for some reason refused an ultrasound, the doctor should then have warned him what the risk was and suggested keeping him overnight for evaluation. If the patient refused that too, the doctor should've warned him of the risk again--by that point most patients would listen to their doctors, and those who don't listen even after all that are not going to win a malpractice suit.