Pedestrians use much less space than cyclists and move slower, they typically also move away when they hear a car and most of them on such roads go in direction opposite to traffic flow so they see when a car approaches. Bicycles go in the same direction as traffic, sometimes swerve and go in small zigzag pattern, they don't have mirrors, don't look back and bicyclists are many times already tired from bicycling, they are also in more hurry than pedestrians (hurrying pedestrians also more often have accidents). In places where there are no sidewalks typically there are almost no pedestrians.