... and compare the prices of these models with those featuring only a simple date or day-date calendar. A "perpetual calendar" belongs to the classic high-horology complications and includes a completely different mechanism than a simple date ring that is switched once a day. This has nothing to do with how often the base movement has to be corrected due to its - smaller or larger - lack of accuracy. It's all about the fascination of mechanical watchmaking, and I think we can agree a cheap radio-controlled quartz watch would be by far more "perpetual" according to your definition than any mechanical timepiece, including Rolex.
Marcus