I think that the AI in games is more like the actions of a person who made a personal decision. So physics is of course something that cannot be ignored for realism, but neither can AI. For example, an apple falls from the tree. That in a game would be the physics aspect. Next example, When enough apples have fallen on the ground, the farmer goes and collects them. That would be the AI. The farmer has decided when to go and get the apples, when most of them have fallen. However, the apple falling from the tree is directed by gravity, a component of physics.