[PeterisP]

The speed limit focus is based on the consequences of crashes - while it doesn't do anything significant (AFAIK) in regards to chances of an accident, there is a significant link between accident speed and rate of deaths and severe injuries.

A car driving at 70 has twice as much kinetic energy than at 50; and modern cars are quite good at protecting people up until they can't - many of fatal crashes would be just property damage if the impact happened, say, 20 km/h slower; while tailgating accidents don't kill much people at all.