A gross misrepresentation contends speed causes great numbers of traffic collisions, injuries and fatalities. If this were the case super highways would be the most dangerous places on earth. They are not. Insufficient regard for road and weather conditions, following too closely, unsafe lane changes and unfit vehicles are the real issues.
Documenting and prosecuting careless and dangerous driving offenses requires genuine priority setting, knowledge and effort but generates a fraction of the revenue of the easy, lucrative speed timing devices.
Speed enforcement bears little relationship to traffic safety. If it did most speed traps would be situated in high accident areas and school zones, but these are not typically where they are encountered. Speed enforcement is primarily stealth taxation, a giant cash cow for local governments.