Evil is more than the momentary lack of good. Like goodness, evil is an active force, a deliberate strategy, an action plan, rife with intention. It’s not just hanging around waiting for something to happen. It lies in wait and then strikes when it decides the moment is ripe.
If goodness had the same drive and determination, it could really get somewhere, but it usually doesn’t. It is too polite, too observant of free will. Good isn’t ruthless.