Let me clarify what I mean here: I'm talking about something that unfortunately happens all too often in my home country where a person decides to complain vigorously at a business of some sort and makes a scene. This is normally accompanied by demanding to speak to the manager and threatening to have people fired over something trivial like being charged 10 cents for extra marshmallows in a hot chocolate.
In the USA these Karens often end up getting shamed on the internet if they end up recorded but other times the Karens end up getting something for free just so they will shut up and go away. I don't know what the motivation of the Karen is but I do know that this sort of approach to the service sector in Thailand is very unlikely to produce calm results on the part of the Thai business owner. Things just don't really work like that here and the corporate structure of businesses here aren't at all "the customer is always right."
For the most part Thai people are too shy and polite to ever cause a scene like this and I honestly have never seen a Thai on Thai "Karen" incident. I have seen some foreigners, sadly often my own nationality, that think that this sort of behavior is a global thing and that harassing a server is going to result in them getting their way. One such incident there was a couple who was complaining that their food was too spicy and they were refusing to pay. The wait staff were actually confused because they were speaking rapid-fire English. Zero concern was exhibited by the tourists and I don't know if they did get their food for free but I do recall one of them saying "it's so spicy that I can't even eat it!" The food in question was red curry. So let me get this straight: You order a curry at a Thai restaurant and then complain when it is spicy? Are you stupid or something?
Who would have ever thought that a dish that is brimming with chilis, has the word "curry" in it, and is being served in a country well-known for their spicy food, would actually end up being spicy? What a shock!
Well recently there was a story in the news about a Pattaya bar owner that didn't take too kindly to whatever the male version of a Karen is called when the female owner punched the guy and knocked him out when he got too loud about not paying a bill. I don't know what the situation was all about but I do know that it is not a good idea to get loud and in the face of Thai people over things like this. The objection apparently was over a 60 Baht bill - which is less than $2.
This was also in Pattaya and the "rules" are a bit different there than they are other places in this country. However, the notion that I am talking about still stands. Thai people are by default normally quite calm and polite but can go into beast mode if pushed too far. Also, if and when the police do turn up, the tables are not going to turn for the Karens. This is not America and police will rarely arrest anyone when there is a fight and they certainly aren't going to side with foreigners outside of the most obvious and terrible situations that are unlikely to ever happen in the first place.
So if you feel as though something has happened that isn't your fault such as you spicy Thai food being spicy or an extra beer ending up on your bill that you didn't order... here's a bit of advice: Approach the situation calmly and politely. You are much more likely to get what you are looking for by going at it this way.
You've no doubt heard the expression "saving face" and this is very important in Thai society. If you push a Thai person to the point where they are losing face, you might end up getting smacked in yours.