W-well... when you have a group of people, those people have basic needs... physiologically speaking.

Even if violence isn't allowed, it'd be possible for disagreements to break out regarding food, water, bed, waste extraction... things like that. Hierarchies could form around what groups control the distribution of available resources, with those on the bottom being the most vulnerable as they have to fend for themselves in a struggle of all against all...

It's a common source of conflict in fiction as well as real-life.