Thais are famous for their service because they are very good at putting on their game face. They know that once they cross from BOH to FOH public area, they must be professional and offer the highest service possible. Thais are very patient and seek compromise rather than direct confrontation. Raising one’s voice and causing a scene is a very Western way of voicing dissatisfaction. It causes the establishment to lose face because it draws attention. Therefore a Thai service professional will do everything possible to quickly diffuse and placate the irrate guest. It works to their advantage to resolve the issue quickly and discretely because oftentimes their English language skills aren’t strong enough to win a shouting match with a Farang.
While you may think that Thais are immune to customer abuse, this is not the case. They just are better at holding their dissatisfaction in and saving face in front of the guest. If you understand Thai (especially Isan dialect) you’ll hear the full rant about a terrible guest once they cross back to the BOH part of the hotel!