In most fables things like talking animals, magic trees and super natural beings are part of the natural world so people are not surprised in these stories. In the farmer's world having a talking tree was not what made the tree useful to him. The farmer worked long and hard to grow the tree and was proud of the the fruits it produced but once the tree refused to carry its purpose the farmer saw no other use for the tree but to become firewood.
Also, the butterfly visited the tree every day until the harvest season was over (4 months) that was enough time to seduce the tree with its tales (even if it wasn't done maliciously) and make it hate its purpose and the farm that was its life.
About the last picture, fire is one of the most efficient and cheap ways to remove a tree stump.