I was thinking only of moving falls. Stationary falls, that makes sense that it would be to the side you put the foot down.

Another reason for left-side falls occurred to me. When you fall into a rut, that rut is reasonably on the right side of our riding path. Gutter area, or off the edge of a paved path. If you try to bounce back out - towards your left - you will fall to the left when that doesn't work.