It's not that fairy tales lack war. When the heroine needs to be separated from her husband post-marriage, well, sometimes there's hunting, but that's not long; certainly not long enough that someone would send the king a message and get back one. And there's the kidnapping options, but that tends to be limited in plots. For one thing, you need a culprit, like her envious sisters or mother-in-law.
So war you have. Its sole impact on the plot is to demand that the king leave his wife.
There's other wars with a little more impact. What better way for the golden-haired prince working as a gardener to rise again than to win the war for the princess's father? True, sometimes he gets his magical helper to give him men-at-arms as well as armor, but sometimes it's just him. Which doesn't argue for a large scale war. Indeed, plots of this type often have a tourney instead.
Perhaps that explains why the nobles are so lacking in influence. No wars for them to fight in.