There appears to be no traffic rules what so ever ..
You want to see no traffic rules, head to India. The direction of traffic is determined by the volume of cars traveling in one direction and lights only work if there is a policeman overseeing the intersection. And livestock has the right of way. Several times we had to wait for the water buffalo to get out of the way before we could get moving when I was there last year. While in Hyderabad, I don't think I ever saw any lane lines either. Or a stop sign. Or orange cones. Madness, for the most part. Riding on the back of a scooter was a bit death-defying as well.
I didn't see anyone wearing helmets but I think what bothered me the most were the pedestrians "strolling" through the intersections......especially the ladies with the kids......jeesh, get the f@ck outta the street!!
Costa Rica was a trip. Watching as motorcyclists would pull out and drive towards oncoming traffic than swerve back into the correct lane. Looking for pedestrians or cars before pulling out was optional. Running across the freeway to get to the mall was accepted and expected. And the ladies... ooh la la.