Teenagers are not adults. Their frontal lobes are not connected and not fully developed.
“"It's the part of the brain that says: 'Is this a good idea? What is the consequence of this action?' " Jensen says. "It's not that they don't have a frontal lobe. And they can use it. But they're going to access it more slowly."”
https://www.npr.org/templates/story/story.php?storyId=124119468