If you were asked why there are speed limits in California, would you say that it's to reduce the amount of accidents that happen? If so, this is a common misconception.
The reduction of speed limits actually started out largely as a fluke. Speeds were reduced in the '70s, by the Emergency Highway Conservation Act, due to the energy crisis. It was only after the reduction that researchers saw that fatality rates had fallen and they began to consider what that meant.
Studies show that the vast majority of accidents actually happen at low speeds. Many people crash at under 20 miles per hour. In fact, one study found that the least amount of accidents happened right around 67 miles per hour.
However, accidents are far more severe at higher speeds -- as you may expect. Fewer people crash at 70 miles per hour, by a lot, but those who do are much more likely to be killed in these accidents. Thus, the reason to limit speeds is simply to help people live through the accidents they are involved in. There is less energy in a low-speed crash.
This is why drivers who are excessively speeding are sometimes charged with reckless driving. They are doing something that is known to vastly increase the odds that someone else will die when they crash. A wreck that should have happened at 20 miles per hour becomes far more dangerous at 55 or 70.
If you have lost a loved one in an accident, especially if a speeding, reckless driver was involved, you may be eligible for compensation.
Source: Tops Lab, "1 Impact of Raising Speed Limits on Traffic Safety," ARUP DUTTA AND DAVID A. NOYCE, accessed June 24, 2016