I agree with the rest; speed is not a cause. It makes it easier to crash if you are already inattentive, drunk, or something else. Also makes the crash worse. But if the behavior was avoided in the first place, then the crash would have been averted. Only exception is people spinning out their cars on turns, which could be said more to be stupidity. The whole 'speed kills' garbage is just justification for unfair fines.
Speed enforcement kills because it takes attention away from the real problems; tailgating drivers, inattentive drivers, drunks etc. Cops who could be doing good are wasting their time enforcing unfairly low speed limits. Case in point, there's this road with some developments on either side and a few houses a way down, but its wide. Huge shoulders too. Has been 50 for years. Residents whined about making it 40 forever. Nothing has really changed on the road, but the county reduced it to 35 (yes, THIRTY FIVE) because they said it couldnt be 40. Guarantee that within 3 years people will get pissed enough to make it 45 or 50 again, but only after hundreds upon hundreds of unfair tickets. Is it unsafe to go 50 there now because some idiots whined and it was put too low? The area is SAFER to go fast in than many 45 and 50 mph roads I have seen. Also, low speed limits contribute to tailgating, as some people try to obey them somewhat (10 over) while the rest continue going their original speed (IE 15-20 over). They're arbitrary often too; same road can be 50 in one place and 40 in another place, or highway at 60 in one state and 70 in another, etc.