A small correction, but there are plenty of reasons someone might require flying. The travel might be required and also be on a tight schedule or terrain might be impractical to traverse by other methods. As an example: a friend of mine had to fly across the continental US for spinal surgery because traveling is stressful on the body and they couldn't be e.g. on a train for multiple days. People move across oceans all the time and might not have the luxury of being able to make a long trip by boat.