What does this mean that "friendship isn't transitive, inherited or reciprocal"?
A: As I grant you friendship access to me doesn't grant your kids automatically access to me, doesn't grant your friends automatically access to me, and doesn't grant me automatically access to you.
I don't essentially trust the kids of my friends. The privileges of friendship aren't inherited. Derived classes of a friend aren't essentially friends. If class Fred declares which class Base is a friend, classes derived from Base don't contain any automatic special access rights to Fred objects.
I don't essentially trust the friends of mine friends. The privileges of friendship aren't transitive. A friend of a friend isn't essentially a friend. If class Fred declares class Wilma such as a friend, and class Wilma declares class Betty such as a friend, class Betty doesn't essentially have any special access rights to Fred objects.
You don't essentially trust me simply since I declare you my friend. The privileges of friendship aren't reciprocal. If class Fred declares which class Wilma is a friend, Wilma objects contain special access to Fred objects however Fred objects do not have special access to Wilma objects automatically.