Well, perhaps your nations are just so-so satisfied with you so that you don't lose the campaign, while I am only satisfied if they are all always exuberant ? Or perhaps you just restart a mission if you happen to lose a soldier ? Upon restarts, the starting situation can be quite different, making the same mission much easier. A civilian life is usually worth more to me than the life of a cannon fodder soldier, this makes me lose lots of cannon fodder. Also, in 2.6 on very hard, if any unarmored soldier is hit by anything, it's a sure instadeath, as the damage dealt depends upon difficulty. This really increases loss rates (and lowers them on easy difficulties).