While I only have one movie on which to base my analysis, I've come to the conclusion that Thai film uses an entirely different formula than American film. Consider this plotline:
A Khmer (ancient Cambodian) princess and her personal witch are captured by a Thai king. The princess and a Thai warrior are in love. The king learns of this and, in a jealous rage, kills the warrior and imprisons the princess with her witch. The princess, mourning her state and fearful of her upcoming execution, is enchanted by the witch with a tremendous spell to bring her immortality. The witch dies in the casting, and the princess's spirit, upon her execution, leaves her body in a glowing form.
Coincidentally, an identical (though unrelated) twin of the Khmer princess lives in a remote village. In the village two boys are in love with her, one of which is evil and plotting. The evil boy attempts to rape the village girl, but the other boy comes and saves her, beating him up. The evil boy goes to his father, who is an evil magician. His father casts a spell on the village girl, and she becomes deathly ill.
It just so happens, however, that the village girl and the Khmer princess die at the exact same time, and the princess's soul (due to the witch's spell) is transferred to the village girl's body. She wakes up confused, a princess in a peasant's body, and begins adjusting to her new role, only to discover that a terrible side-effect of the spell is that she has become a will-o-the-wisp. As such, each night her head and entire gastrointestinal system pulls out of her body and flies around in a fiersome and disgusting form, where she kills farm animals and feeds upon their intestines.
Ok, that's the plot, and so far this would fit the American mold. Were it to be an American movie, I predict the plot would finish as follows: the girl would struggle to control her evil side while using her newfound power to avenge the village girl's death (by killing the evil wizard), avenge her own death (by killing the king), and ultimately set things straight before overcoming her evil self but only at a sacrifice to her own life, where she then goes on to heaven and the will-o-the-wisp is destroyed or goes to hell. Basically, the moral is "good triumphs evil, and fight fire with fire."
However, this isn't America, Toto. In the Thai version, the king is never mentioned again and gets away Scott-free. The will-o-the-wisp starts killing indiscriminately and the girl becomes basically an evil, willing participant. It starts out with farm animals, which are blamed on a local crazy woman, but eventually starts killing people. One of the first human victims is in fact the evil boy who killed the village girl, though more out of convenience than out of vengeance. The evil wizard tries to kill the girl but she uses the love of the good boy to rally the village to her side, as well as a monk from a local Buddhist temple. The wizard and the monk get into a fight, and the monk casts a counterspell that burns him to a crisp. The monk also takes custody of the crazy woman, who after being cleaned up and made pretty, everyone starts worshipping. The boy and the village eventually learn of the girl's deception, and the monk goes to kick her ass. He casts a spell, and the will-o-the-wisp is separated from the Khmer princess's soul. The princess goes to heaven. The wisp turns out actually to be the princess's witch, who gets in a fight with the monk but loses, eventually incinerating her down into a pile of ash. The monk leaves, the village is in turmoil, and the last scene is a young village ferreting through the ashes, only to find a wooden bead necklace. She of course wears it, and her eyes become the wisp's evil eyes. The End.
So basically, the best moral of the story I can find is "Even if you're crazy, if you're clean and the monk likes you, you're good. Also, the monk can overcome evil, but only temporarily. And finally, if you're caught in the crossfire, too bad."
In the scene pictured, the evil village wizard (center) is about to be incinerated by the monk.