It doesn't have to be. What makes it difficult is our rational minds. If we turn them off, finding agreement on things is automatic. It's literally how herd animals operate.
One thing I take notice of when we go out on team lunches is how the decisions of which way to cross the street or exactly when to cross are made. One person takes a tentative step, then the whole group moves, on automatic instinct. Nobody really cares about when and how to move, so any random impetus gets picked up on. We all kind of notice it and sometimes it bubbles up to a conversation where we rib each other, in good fun of course, on those random impulses that then drive the whole group.
The decision for where to go for lunch is also similarly painless, pain is introduced when too much thought is given to the decision. We collect ideas from everyone who has a feeling, then come to a group consensus on where people want to go. It's only when you forget that there's a instinctual way to handle group consensus, when you engage your cognitive mind, when you think about what to do, that it becomes difficult.