Ought not to exist in places like Europe, perhaps.
The four-way stop has the virtue that it is easy for Americans and Canadians to understand.
1. Everyone arriving at the four-way pretends to stop by slowing down to around 20 mph.
2. Regardless of who arrived first, if two or more vehicles take conflicting paths, the biggest asshole goes first. (The algorithm for determining this party takes into account factors such as vehicle size, general socio-economic background, minimum velocity achieved during four-way stop approach, and their apparent perception of where the white stop line is.)
3. When two vehicles take nonconflicting paths (e.g. two directly facing vehicles both go right) they need not acknowledge each others' existence.
4. Only left turns must be indicated. If someone fails to indicate while approaching, they are assumed to be going straight or turning right. Should that be incorrect, the situation is resolved by a fair division of rights: right of way is given to the non-indicating left turner($), whereas the inconvenienced/threatened party is given the right to several prolonged honks of the horn.
5. Where visibility over the other converging roads is not obstructed by building, bush or otherwise, the four-way stop may be completely ignored when not approached by another vehicle with an estimated arrival time that is within a second, either way, of one's own arrival time. (Pedestrians and cyclists may optionally be counted as vehicles at the driver's discretion.)
Who needs roundabouts?
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$. The governing principle here is consistency -- with rule (2).