Alright you know what, let's take the politics out of this and make it purely about economics, the free market, and individual rights.
If I have wares/goods that currently belong to me, my property and I want to sell them to you ...I get to charge you whatever price I damn well please. That's my right, my prerogative.
If your friend comes along and wants to buy the same goods, I can charge him whatever I want to charge...even if that's a different price than the one I quoted you.
Is that fair/ethical of me? Perhaps not, but this isn't kindergarten and we aren't little 6 year old girls, we are full grown adult men, so fu cking deal with it, it's reality.
Is it smart business by me? Probably not, but the free market will decide all, so if it's bad business by me ultimately the market will punish me for it, by seeing all my potential customers go to someone else.
The Thais didn't ask you to come to their country, many of them don't want you in their country at all. None of them forced you to go there, none of them are forcing you to stay there and none of them would lose a second of sleep over it of you were to leave tomorrow and never come back.
It's their country, not yours. You don't have the rights and right to expectations there that you seem to believe you do. You are a guest there. They are graciously allowing you to stay there. They don't have to be doing that.
It's not your home, you aren't one of them, you aren't part of their land and their community, you are a farang. No matter how long you may live there for you will always be a guest, a farang guest and nothing else, nothing more.
This applies for all of us by the way, not saying it's just you.
Bottom line is...
It's their country. They can do what they want in their country, and it's not up to you. If they want to charge you a different price than they charge their fellow countrymen well that is their right and their prerogative. They can do that.
You don't have to like it, but then you know what...
Once again, no one is forcing you to live in Thailand, you're choosing to do so of your own free will.
If you aren't happy with something there your options are
1. Shut up, man up and just fu cking deal with it.
2. Decide you just can't accept it and try to do something to change it (lol, good luck with that.)
3. GTFO of the country. (like I said none of the Thais will miss you, it's absolutely fine by them if you take this option.)
You apparently chose option 4, which is to bitch and moan about it on an internet message board. That's a common option chosen, you are far from the first to choose it, only problem with this option is it doesn't change one thing, not one damn thing.
If you actually want to do something about the problem, I suggest choosing one of options 1-3. Probably 1 or 3. 2 would solve the problem in the way you want but that would first require you convincing Thais to actually listen to the opinion of a farang as to how they should do things in their own country, and you're never going to achieve that.
So I'd suggest 1 or 3.