Gentlemen,
The hard fact is that AI traffic does not strictly obey COLREGS, and never will. Where possible, AI ships will slow, stop, or change course to avoid you, but only within their normal maneuvering capabilities (stopping distance, ROT, etc.).
Their avoidance capability also depends upon the commands given to them by the creator of the mission. Unfortunately AI is used inappropriately in many missions.
You, the player, should operate under rule 2 at all times. You are expected to be on the lookout for AI and stay out of their way. All of your complaints will not change that fact.
AI behavior may be improved over time, but the only solution in the short term may be to remove all AI from the free roam environments.
AI was never intended to be used as scenery, but only to serve some function in the story of the mission, or to present a challenge to the player.