It`s a matter of scale (among other things); the actions of the French armies in Spain and Portugal dwarfed anything else in that period. N`s ignoring supply logistics led to all his generals following suit.
If their commanders did not provide food, the men just went and took it, with all the violence and brutality that had to follow.
Those same French commanders in Spain and Portugal turned lots of blind eyes to what was going on and many were busy looting and lining their own pockets as well. Extraordinary state of affairs.
Allied looting in France in 1814 was very limited, at least under Wellington. I have yet to hear about large-scale allied pillaging in 1815.