C++ Primer, Fifth Edition

Normal Protection Rules Apply to Local Classes

The enclosing function has no special access privileges to the private members of the local class. Of course, the local class could make the enclosing function a friend. More typically, a local class defines its members as public. The portion of a program that can access a local class is very limited. A local class is already encapsulated within the scope of the function. Further encapsulation through information hiding is often overkill.