Your roof-blowing-off analogy is absurd. A roof is a necessity: It is an integral part of a house, that has to be there. To ask a neighbor to remove his roof so it will not blow off and hit your house during a hurricane is to ask that person to destroy the functionality of his house. Therefore, a roof blowing off, if it happened, is to be considered to have been unavoidable, and the consequences unavoidable. A tree, on the other hand, does not have to be there. A tree on someone's property, that poses a menace to someone else's house, can be cut down or shorter without at all hampering the tree-owner's ability to use his property for its basic function.