St Luke reveals to us some of his mastery in literature. Using the device of a pair of related stories, when to make the point only one would be more than enough, is a device that emphasises the importance of our Lord's message.
And the message is - God will go to extended, unimaginable efforts to save any lost ones back to his family.
It can be easy to feel sad that someone we know and love seems to be far away from God - for example a grown child who no longer comes to Mass. There is a lot of comfort in the sure knowledge that even those who no longer seek the Lord, are being sought out by God - He never abandons even the least of the little ones.
Our part is both easy and difficult - keep on loving and praying for them, no matter how little the effect seems to be. God has everything in his care.