Whatever the case, it is up to those parents to help bridge the gap from the moment a teenager is state-sanctioned to drive and the time when mature judgment has evolved. Make clear that driving is a privilege that becomes a right only within observance of the rules. Agree on the consequences of any failure to follow these rules. No riding with drivers who have been drinking, no passengers who have been drinking and no alcoholic beverages in the car, open or unopened. Establish your own system anyway gradually increasing the privileges for your young driver as time and compliance dictate.
Transgressions throw the process back to square one.
An upgrade to pleasure trips. The next level could be carrying one other teenager. To carrying two or more teenagers with a designated adult. To night driving. To trips out of town.