A kidney stone attack can have very similar symptoms to an acute appendicitis (searing pain around the abdominal area, vomiting) which qualifies as an emergency. It is possible that an accurate diagnosis could not be performed on site.
Other than that, kidney stones are among the most painful afflictions there are. Patients are best brought to a place where windows can't be opened as some may decide to jump out on the spot. They will do anything to get the pain to stop, and a guy like Bezos just happens to have some resources.