I personally did not accuse anybody of being deliberately rude. People are different; some are more sensitive to how they are treated than others. I suspect that those who don't care that much about how people treat them don't realize how a similar treatment would affect people who do care. Some people might feel that they are being ignored if a seller doesn't acknowledge their feedback. It's very possible that those merchants who did not send thank you's were not aware what it would mean to their customers. This is why it's good to bring this question out in the open. Several people in this thread made remarks that they had not been aware of this issue and they will pay more attention to this in the future. It's a little bit like when you notice that somebody is mad at you but they wouldn't say why. You ask them, "What's wrong?" and they say, "Nothing". Wouldn't you like to know what the problem is, so that you can clear it up?