Bad/inattentive drivers do....
Actually, from what I've seen in analysis of such things, it's differences in speed that causes accidents. That's why there is a minimum speed on most interstates.
A while back when Montana changed their interstate speed limit from a hard number to "reasonable and proper", the overall speed increased, but fatalities actually dropped, because people are actually better judges of what R&P is than you'd think. If everyone is driving 90 mph, the road is no less safe than if everyone is driving 60 mph. What causes problems is when you get some bozo poking along at 50 when everyone around him is doing 90. That 40 mph difference is what causes problems.
Exactly!!
Hell... There should be a MINIMUM speed of 60mph for cars. Anyone going under gets a ticket, as a speeder would get today. Of course, this can’t apply to trucks, ect.