I’m sure there’s plenty of examples but I’m going to share one from my work experience.
We had a patient who survived a really bad car accident but their jaw was broken in 4 (four) places. One of those cases when the doctor will wire your mouth shut leaving a small hole for the straw so you can drink your soup for the next x weeks.
The patient had a facial reconstructive surgery coming and their surgeon ordered an MRI of their jaw to see where the pieces were before cutting them open. The patient, unfortunately, had one of those cheapo insurance plans that were provided by their employer. Said insurance denied the MRI authorization 3 (three!) times due to “lack of medical necessity”. It took us literal hours of arguing with that arsehole adjustor and their supervisors on the phone until they finally approved it.