In St. Barths, tipping customs can vary depending on the establishment. Generally, tips are not included in the bill at restaurants, similar to mainland France. However, it's always a good idea to double-check the bill or ask the staff if you're unsure. While tipping is not mandatory, it's appreciated for good service. Regarding the strategy you mentioned about waiters in the south of France, it's possible that similar tactics could be employed in St. Barths, but it's not a universal practice. Ultimately, tipping is a personal choice, but it's always nice to show appreciation for excellent service.