Just because people aren't wearing the uniform of the enemy doesn't mean that they aren't the enemy. During wartime, many civilians contribute to the war effort by working in military factories, by raising and preparing the food that the soldiers eat, by collecting and recycling materials used to manufacture various war supplies and weapons, by being lookouts for enemy aircraft, etc.
by your inane argument, there should be no difference in the Geneva Convention between combatants and civilians.
That's an interpretation that NO nation has.