You have to remember that many people on here probably don't own a car, or necessarily even hold a driver's license. They most likely either live at home or at school, or take a bus to work (NTTAWWT).
As far as I understand your comment, driving at the speed limit is unsafe because everybody is speeding. Sounds like a self-fulfilling thing. Maybe it would be even safer if the majority would obey the speed limit?
Did you read the link I posted? Theres lots of empirical data out there that says that drivers drive the same speed on a road, regardless of the posted limit. That speed is based on their judgment of the road - sight lines, shoulder width, sharpness of curves, etc.
-- 55% of drivers regularly exceed the speed limit, meaning that the speed limit represents the 45th percentile speed
-- driving between the 50th and 90th percentile speeds is the safest
Taken together, driving at the speed limit is significantly unsafe.