Distraction
Research suggests that the drivers attention is affected by distracting sounds such as conversations and operating a mobile phone while driving. Many jurisdictions now restrict or outlaw the use of some types of phone within the car. Recent research conducted by British scientists suggests that music can also have an effect; classical music is considered to be calming, yet too much could relax the driver to a condition of distraction. On the other hand, hard rock may encourage the driver to step on the acceleration pedal, thus creating a potentially dangerous situation on the road.Cell phone use is an increasingly significant problem on the roads and as the U.S. National Safety Council compiled more than 30 studies postulating that hands-free is not a safer option, because the brain remains distracted by the conversation and cannot focus solely on the task of driving. Intent
Some traffic collisions are caused intentionally by a driver. For example, a collision may be caused by a driver who intends to commit vehicular suicide. Collisions may also be intentionally caused by people who hope to make an insurance claim against the other driver, or may be staged for such purposes as insurance fraud. Motor vehicles may also be involved in collisions as part of a deliberate effort to hurt other people, such as in a vehicle-ramming attack. Combinations of factors
Several conditions can combine to create a much worse situation, for example:

Combining low doses of alcohol and cannabis has a more severe effect on driving performance than either cannabis or alcohol in isolation.
The summary says:

The evidence shows the risk of having a crash is increased both for vehicles traveling slower than the average speed, and for those traveling above the average speed. The risk of being injured increases exponentially with speeds much faster than the median speed. The severity / lethality of a crash depends on the vehicle speed change at impact. There is limited evidence suggesting lower speed limits result in lower speeds on a system-wide basis. Most crashes related to speed involve speed too fast for the conditions. More research is needed to determine the effectiveness of traffic calming.In the U.S. in 2018, 9,378 people were killed in motor vehicle crashes involving at least one speeding driver, which accounted for 26% of all traffic-related deaths for the year.In Michigan in 2019, excessive speed was a factor in 18.8% of the fatalities that resulted from fatal motor vehicle crashes and in 15.6% of the suspected serious injuries resulting from crashes.The Road and Traffic Authority (RTA) of the Australian state of New South Wales (NSW) asserts speeding (traveling too fast for the prevailing conditions or above the posted speed limit) is a factor in about 40 percent of road deaths. The RTA also say speeding increases the risk of a crash and its severity.