It's not "fake" - it's cultural differences where what is intended to come across as polite by Americans[1] can be seen as insincere by people from elsewhere. On the flip side, Americans often view foreign behavior that's intended to be neutral as unfriendly, uncaring or cold.

1. e.g. lots of smiling, use of superlatives like "great"/"amazing" to describe mediocre items/effort/results