Why can't they all be right? It's not like there's a big man in the sky telling everyone that wars must only be fought between two opposing sides with identica

Why can't they all be right? It's not like there's a big man in the sky telling everyone that wars must only be fought between two opposing sides with identical motives on a logically comparable continuum. It's not even like wars must even be based on positions that can be meaningfully called right or wrong. Or that most wars can be meaningfully interpreted as "two sides". Even within the allies of world war 2, you would have a variety of factions and motivations, as well as minority players with diametrically opposed views and beliefs.