Why Do the Vuduri Speak So Formally?

Many people notice that the Vuduri speak extremely formally. The reason for this is because the Vuduri do not normally speak at all. The Vuduri language contains no contractions, no slang, no idioms. It is just a way to communicate thoughts. So when they do decide to speak out loud, their speech sounds almost mechanical. I suppose that the mandasurte might have a dialect and use contractions but they never communicated that to me.