From time to time I get phone calls from parents concerned about their child's driving and asking for advice.
First I would take a long hard look at your own driving. If you've ever said "Don't drive like me", this is a sure sign that your driving could probably improve. Your bad habits could seem mundane and not quite so serious as driving 60 in a 35 zone, but to a young person, your a bad driver too. You might say "yes I could use my turn signals a little more often, but at least I don't text and drive". You are older and can evaluate risk better than a young person. Even if a your person can differentiate types of risk they might not care because there could be a culture of risky driving in the family. Many young people follow the basic rules of driving except when it comes to speed and texting. All while most adults follow those rules and actually don't follow the basic rules their child obeys such as turn signals and complete stops. I guess you have to ask yourself how well of a driving role-model are you? I would start off the conversation like this...
"I'm concerned about your driving [include specific examples here] but I also know that I'm not the best either. So I'm going to try to be a better driver just as I'm asking you to take driving more seriously. I don't want anything to happen to you...."
This strategy could work but if it doesn't you might have to use different strategies. The first is scaring your child into driving safer. I recommend enrolling in the Idaho State Police program called Alive at 25. Also watch the movie "Red Asphalt". You could also watch real emergency room videos of actual people involved in accidents. Please be warned that "Red Asphalt" and some emergency room video can be quite graphic and may cause mental and physical discomfort. Go to Alive at 25 and watch any videos with your child.
Another strategy might be to enroll your child into another driver training school. I would go with a different school than before. Many judges actually require drivers to retake driver training as part of their judgement. A "Traffic School" reduced points on a license and is also 6 hours of additional classroom training for drivers of any age. While teens may not learn a whole lot from these options they will absolutely loath the idea of driving in a drivers training car again or sitting in a classroom for 6 hours (I believe the Alive at 25 class is 4 hours). Many driving instructors remove the signage from their cars because they don't want people to think they are learning to drive - imagine how a teenager who took drivers training will feel. They will feel like it is punishment - and that's perfectly okay - whatever it takes to get them to drive safer.
Another strategy should be to let your child assume all responsibility when they get a citation. Do not pay the ticket for them. Don't even take them to city hall or court - tell them to take the city bus. You should only be involved if legally it requires a parent signature or other situation. The purpose is to make the entire process part of the punishment. Also you should immediately stop paying for gas, insurance, registration or any other fees.
The toughest strategy is taking away the keys. Never give a time frame such as "you've lost your driving privileges for 30 days" or "your gonna lose your keys for 30 days if....". Just simply take their keys. To facilitate these consequences easier you might create a driving contract with your child. That way you won't seem like such a bad guy when you have put the hammer down. This is an excellent time to use the car keys as leverage to do better in school. If you do say "30 days no driving" or something similar - you must keep your word. So as much as you'd like your child to pick up the younger brother from soccer - you cannot let them drive - you must drive. Ultimately, you must make punishment realistic for both of you. Allowing your child to drive with you in the vehicle is a great way to mold them into a better driver. But be careful you will be judged as well when you drive and your child observes you. Please re-read the second paragraph if you use this strategy. Don't be a "do-as-I-say, not-as-I-do" parent.
Another easy strategy is to pay for the fees for their license with the added agreement that the actual drivers license belongs to you - simply take away their license - then they can't find that spare key or drive their friend's vehicles (which actually happens a lot).
If your child keeps texting and driving then take away the car keys and license, not the phone. They need their phone to text their friends to pick them up (this is very embarrassing to a teen and a form of punishment).
Some of these strategies might take time from your day or might be challenging to enforce but if will be worth it. Young drivers gradually taking driving more seriously when they hear stories of friends who have gotten in trouble, injured, or killed while driving. Driving is a privilege that can easily be taken away by many different means - what they need to understand is that they have control and can stop that from happening the majority of the time.