[LesLattis]

I always thought of "hello" not as a greeting on the phone but rather a way to establish that you are being heard. like, you call someone, they say "hello" to answer the phone, and then you go on saying "hello, good morning / afternoon, I'm calling you to...." whatever. so hello is not really the greeting in itself.
I guess I am transferring our Hungarian phone etiquette to English.

as for "thank you", let me clarify. at my school, when you sit down at the teachers' tables in the canteen, the lunch ladies bring you a plate of fruits or snacks, and a jug of water (it's not self-service). farangs look up and say "thank you", Thai teachers don't look up and don't say anything. they don't tell farangs off for saying "thank you" but if you try to ask them why, they express their surprise at the farang habit of saying "thank you" all the time and explain that you don't need to say thanks to service staff.
I am having a hard time teaching my students (aged 5-6) to say "thank you" when I hand out snacks, pencils, books, homework, anything. they just don't get it. even though I think you are supposed to say "khap khun khrap/khaa" in Thai when handed something by an adult. I guess it comes from home. in Hungary, this is the very first thing kids are taught to say by parents, to greet adults and to say thank you. - not that we are a nice and polite nation by the way! on the contrary. service staff is notoriously rude in Hungary for example, I wouldn't thank most of them for anything because they almost hurl your tickets / weighed vegetables / change at you. but the kids can do it properly before they go off track.