Not only that, but even what an outsider might think of as the same plane is unique per customer. Qantas wants the holes for the lavs here, while JAL doesn't c

Not only that, but even what an outsider might think of as the same plane is unique per customer. Qantas wants the holes for the lavs here, while JAL doesn't care because they are going to use it for an all cattle class commuter flight. The manufacturers fight it, but at the end of the day the customer is always right.