Honestly, I think the main thing is their upbringing. If a kid is raised to be responsible, then driving is less likely to be an issue. Today, kids are being taught that they need to "be kids" and it's ok to "go wild" before they become adults. Too many parents are raising *children* instead of training children to be responsible adults. Too many children are staying children instead of learning responsibility, courtesy, and ethical behavior.
Sorry, I guess I jumped on a soap box there.