Sometimes when we do what we think is polite, can be interpreted as rude by others. For example, when we are visiting as guests; in American customs the host would ask the guest about his/her preference, such as what drink to serve, hot or cold, with sugar, milk, or even add cookies :). In Indonesia, it depends, the host will adjust according to his closeness to the guest, but would most likely offer options. In Japan, the host never ask the guest about his preference. (This is just simple generalization for comparative analysis).
“Please help yourself” can have an unpleasant ring on Asian ears. The Asian traditional sensibility interprets it as “nobody will help you” instead of “please take what you want”. Nowadays as people get more exposed to foreign culture, they have more sense to tolerate and understand these cultural differences.