Why does C++ not allow inherited friendship?

Question

Why is friendship not at least optionally inheritable in C++? I understand transitivity and reflexivity being forbidden for obvious reasons (I say this only to head off sim

Answer 1

A friended class may expose its friend through accessor functions, and then grant access through those.

class stingy {
    int pennies;
    friend class hot_girl;
};

class hot_girl {
public:
    stingy *bf;

    int &get_cash( stingy &x = *bf ) { return x.pennies; }
};

class moocher {
public: // moocher can access stingy's pennies despite not being a friend
    int &get_cash( hot_girl &x ) { return x.get_cash(); }
};

This allows finer control than optional transitivity. For example, get_cash may be protected or may enforce a protocol of runtime-limited access.