Driver training or lack of it,
Most people had 10 or 20 driving lessons when they were 17-20, took a very basic test and passed, now years later the cars they are driving are faster, more powerful with gadgets to help with everything but the driver is still the same person with little or no training, eysight and reaction has deteriated.
Through my job i have had equal to 3 month driver training which according to the Institute of advance motorist put me in the top 2% in the country, biggest thing i learnt is to know your limits, not the cars.
Speed is as a result of over confidence, same as agression.
We all have sworn at the bloke doing 80 in the rain in the outside lane and then at the crawler doing 20 on the inside lane.
A stricter initial test and re-testing would be a better way to reduce accidents, restricitng cars...why do you need a car capable of 160mph or with a 4.5L engine when the limit is 70.