Well thought out explanation, I couldn't say it better.
The belief in magic and mysticism runs deep here.
She doesn't sound willing to listen to you, nor accept your logic; I'd say it's pointless to fight it.
Like BangkokReady suggested, just "do what you want, and try to ignore her."
Resistance is futile. They have been assimilated. Take the good with the good; try to see it as your free education into Thai-ism, and try to avoid being supremely frustrated. It's bad for your mental and physical health.
Surely there's a humorous side to all this? Who knows, she COULD be right, .000001% of the time! ????
Edit addendum: There ARE occasions where "The Thai Way" will make better sense (in Thailand, or in Thai situations)... surprising, to our Western mind, but nevertheless true.
Have you EVER been able to teach her ANYTHING, or open her mind to a different way of seeing or understanding ANYTHING? Even once?
