Thais admire serenity and regard overt expressions of emotion as immature and unsightly. This is especially true in the case of anger or impatience. If you show anger, you will immediately lose the respect of Thais. Their first reaction will be to laugh at you, in the hope that you too will remind yourself of the absurdity of trying to solve anything in this way. You still have time to smile off your momentary lapse. In Thailand, if you have a point to make, you will have to make it with quiet non-aggressive eloquence and show potential goodwill to the person you are talking to throughout.
Newcomers to Thailand are sometimes shocked when Thais convey bad news, such as the death of a parent, with their faces wreathed in broad smiles. For Thais, showing a smiling face to other people, no matter what your personal problems, is a basic kindness and a mark of emotional maturity. They are made very uneasy by what they see as the curiously miserable or scowling faces of Westerners. This doesn’t mean Thais don’t have the same sorrows and sensitivities as the rest of us.
Yeah as i said. Eventhough it's "Land of smiles" we too get upset with same reasons that you do. But you'll find the way people here deal with anger in some strange ways.. like pretendning not to hear you when you shout "So where is my ticket?!" or slowing down everything when you ask them to be fast.. etc..etc
So "Jai-Yen" (cool-hearted) you'll get what you want anyway just be patient.
I'm sure you know this already as it's a common sense. Getting mad at people won't bring you anywhere. For example some travel agents are amazingly slow to organize things you ask for. Best is to deal with them with a serious tone of voice not yelling or shouting (Well, unless they yell at you first which doesn't happen often) Everytime I join the trips with big groups of travellers there's ALWAYS someone got upset and stated to yell at someone to make him feel better.
Louder you yell, more they will ignore you. That's a fact.
In Thailand, almost everything in life involves a smile, even blunders and mishaps. Westerners often mistake this for being laughed at. For example, if a waitress forgets an order and laughs, she is not showing contempt, just making the best of a bad situation. If you complain, do so gracefully as anger usually gets you nowhere.
Outward expressions of anger are regarded as crude and boorish. Remaining calm and hiding your emotions with a smile is far more productive.