Because they get automatically destroyd when they get out of scope.
The soul is dyed the color of its thoughts. Think only on those things that are in line with your principles and can bear the light of day. The content of your character is your choice. Day by day, what you do is who you become. Your integrity is your destiny - it is the light that guides your way. - Heraclitus
Local variables or automatic variables are declared in methods of a class.These variables are loaded when a objec method is called and destroyed when the method completed. Thus it is called as automatic or local variable.