In their own recent study, a government report stated that speed was the primary factor in only 7% of accidents.
I'm not saying that speed isn't an issue, or shouldn't be reduced, especially in towns etc., but it does bug me that it has been seized upon as the main culprit of all accidents.
It is a factor, yes, but a much larger factor (14% as I recall from the same report) is a lack of driver observation (not seeing the other vehicle or not assessing speed correctly). However, speed can be easily detected and punished; actually training people to a higher standard would cost the government money.