There are many reasons why young drivers are more likely to be in crashes than more experienced drivers.
Lack of Experience
This is one of the main reasons. As new drivers gain more experience, their crash rate begins to fall.
Young drivers, especially men, tend to be over confident and are more likely to drive in risky ways. They consistently rate their own skills as above average, despite the fact that their accident risk suggests otherwise. They commonly see 'good driving' as the ability to master the controls of the car at higher speeds.
Hazard and Risk Perception
Although younger drivers tend to have excellent vehicle control skills and fast reactions, they are poor at identifying potential hazards and assessing risk. They tend to over-estimate their ability to avoid the hazard and its consequences. It takes new drivers up to 2 seconds longer to react to hazardous situations than more experienced drivers.
Younger drivers are more susceptible to peer group pressure, especially when carrying their friends. Their risk of crashing increases with the number of passengers in the vehicle.
Young male drivers are more likely to commit driving offences or be involved in an accident than female drivers.
Source - www.helpingLdrivers.com