They can’t do it that way because the question of right of way only matters when two boats are going towards each other. The coloration is an easy visual indica

They can’t do it that way because the question of right of way only matters when two boats are going towards each other. The coloration is an easy visual indicator of where a boat is generally going that doesn’t require seeing any other part of the boat to work, and will even work in fog. You cannot safely flip the directions for any fraction of the boat’s travel.