The system of buoys developed independently in the Western hemisphere—principally in the US and Canada. In the US, it developed first on the Mississippi River.
When the first hazard on that river was marked, red seemed to be the natural choice for the color. That hazard happened to be on the East side of the river. Another reason often given was that it was done to confuse the Brits if they tried to come upriver to take St. Louis.
Canada followed the same convention because we share the St. Lawrence River—to do otherwise would have made navigating that river exciting.
Our B system spread to countries in the Western Pacific by our heavy trade in that area, and our publishing of charts by the Hydrographic Office under Mathew Maury.
European nations trading in that area had their own charts, of course. That theirs were not adopted locally might be due to their being considered proprietary commercial or military “secrets†by those nations.
