But the website you provided said that the colonies changed over gradually to driving on the right. That just plain doesn't make sense to me. You would think that it was an all-or-nothing proposition. I cannot imagine meeting another wagon on a road and having a polite discussion as to whether to go right or left to pass the other vehicle.

Maybe in the beginning, people mostly drove their wagons in the vicinity of their homes, and rarely ventured far away. Then it would be possible to have places where everyone drove on the right, and other places where everyone drove on the left, and possibly not much mixing of people and wagons among them.