Jesus' parents were astonished when they found him in the temple courts, sitting with the teachers listening to them and asking questions (v.46). Were they astonished because they expected to find him playing with the other children, rather than conversing with the adults? Were they astonished because they expected him to be upset about being left behind? Were they astonished because he wasn't concerned about their feelings?
Mary said, "Why have you treated us like this?" As if she sees Jesus' behaviour as a deliberate attempt to cause his parents grief, instead of his curiosity with the things of God. Jesus was twelve and considered an adult in Jewish society. Jesus knew it was time to grow up and start taking his destiny seriously. He needed to learn as much as he could while he was in Jerusalem and had access to the teachers there.
Still I suspect people today still say to Jesus, "Why have you treated us like this?" Why have you allowed this anxiety, this worrying turn of events or this inconvenience? You must have known this situation would cause us to worry unnecessarily. You could have intervened sooner and prevented it? Often we expect Jesus to be more concerned with our comfort than his purposes and then wonder why we feel abandoned.
Yet today we always know where Jesus is. He is with us and in us, even when it seems otherwise. He always cares. Yet his heart is for his father's business, for those things which are important to God. His presence is not merely designed to keep us happy and comfortable.