"For those that don't shout, what would you do if one of your siblings hit the other one, or ran out into the road when you had to told them to hold your hand? Surely some situations warrant a raised voice? "
A sibling hitting another would get told off. In no uncertain terms. But not loudly - firmly, annoyedly, but not loudly.
What would you do if a colleague needed reprimanding (assuming you were their manager). Would you yell, or would you deal with it calmly and professionally?
Yes, I deal with my children quite a bit differently than I deal with colleagues, but the point I'm making is it is possible to express displeasure and ensure its understood this kind of thing should not happen again without actually yelling.
A child who broke free of my hand running towards the road? I'd probably yell in that situation, yes. Partly because there is likely to be noise to be heard above, if there is a car that close and traffic in general. Partly because of the sheer urgency of the situation and the grave consequences - that's the kind of thing that would make me raise my voice, yes.
Like I say its not a concious decision or parenting philosophy, just the way I am personally programmed. Bear in mind also my children are thus far both pretty "easy" to parent, we've got thorugh the "terrible twos" with no episodes I could honestly describe as a tantrum. Why? He's programmed a bit the same as me, I guess! (He does yell though in other ways!)