It may be true. People in such places are regulary brainwahsed that they live in the happiest place. Only few of them have access to information from sources other than the government ones.
Besides, they are occupied with sustaining their basic needs, so when they succeed in it, they feel really happy. When you manage to get a piece of bread to you or you family, you'll feel happy that you or the family are not going to starve.