The kindness of strangers is so often a blessing. It is another proof of goodness, truly Godliness in this world. This is a great thing. Seeing how beautifully we louse things up with the people we know, it's good to know that there are strangers who are willing to help.
The beauty of being a stranger is that when the opportunity to be kind presents itself, we decide based on our own compass, without having to factor in the degree of the damage we've already taken.