We don't - which is handy because Governments need them to go off and fight in wars. I dislike the subjectivity, you either raise the age of adulthood to something closer to 25 or you trust that young men and young women are adults and let them crack on with making good decisions and bad decisions alike.

I made the counter argument here if you're interested. https://medium.com/lucid-nightmare/leonardo-cradle-snatcher-di-caprio-and-the-vagina-patriarchy-9b9bed8a43f1