I dunno about that.
These parents were about as responsible and respectible as anyone I've ever met. The sister was just being a stupid kid, rebelling against everything around her.
Then she was trolling for attention from her parents. Saying things openly which are contrary to your parents values is making a statement.
Either they were ambivilent to certain types of theft, or she was challenging someone to tell her parents that she disrespected them. If it was me, I would have obliged her, or at least confronted her on whether they had taught her that stealing was ok.