Oh it’s not traffic. They are often quite empty. British country roads are narrow and often stone wall lined, or tree lined, or embankment lined, or all three. They are winding and can be quite steep. Corners can be almost back on themselves. Often there are bits down to a single lane for both directions, with passing points for someone to wait for the other direction to pass. If you encounter someone who can’t reverse, you might have to reverse quite a way.