Basically, if you want to stay in Thailand and teach here in the long term without having this mental anguish, which many teachers seem to be afflicted by, then you simply have to get over the idea that you can change anything in a meaningful way (especially in the education system). Accept that they don't care what you think, that you are simply there for show, suggestions from you are viewed as unhelpful and unwelcome (even if politely listened to).....in other words "Don't give too much of a shit about it all" and know the limits of what's possible and what's not from your position as being unrealistic will only be personally crushing at some point for you.
Accept that they are like how they are, it's their "gig", get over the "I'm going to make a difference to the school" sort of thinking, go with the flow of the river and view it as a means to an end. Work shit only gets to you if you let it.
You will be a lot happier if you take this stance. I work here to help my family and I stay together here where we are happier than we would be elsewhere.......I'm not here to save the Thais from their inept education system, up to them imo to save themselves and little will change as it's the crusty dinosaur brigade that is generally in charge (when you see them in their office they strike you as the type that could quite easily sentence 5000 people to 20 years slave labour without batting an eyelid about it). I just do what I have to do to see it through to the end of the month, do a good job, not attach importance to the silliness I encounter, save as many Thai students as can be saved or who want to be saved and go home for a glass of red wine and have dinner with the Mrs.
I'm way beyond trying to rationalize the ridiculousness and lies I encounter on a daily basis. Got to learn to just let go of stuff and let it just flow over you, just the way it is here folks.....otherwise you'll end up unhappy, frustrated or insane (or a combination of all three).
As a popular saying says "Free your mind and your ass will follow"......how true.
I spent the first 7 years of my time here working in the 'run-of-the-mill' places and they were sloppy, unprofessional and couldn't care less about what I (or anyone else for that matter) said. I've finally found a good place to work in and it will probably be my last teaching job here.....starting a business later will be the way forward, then teaching will become just a hobby to do part time when it is conducive to me.
However, some might say I've been here too long and am too cynical.......which I understand, but it does make me smirk when I hear that.