This is a very popular argument. I run into it a lot. I have been criticized for following the speed limit when there were six vehicles spaced across five kilometers. It seems I am expected to speed up to match the one vehicle that passed me.

If nobody obeys the speed limit and it is in fact safer to exceed the speed limit, why do we have speed limits? Why does the government make it illegal to do the safest thing? And why does the public put up with it? Why is there no MADD-like organization protesting the insane government policies that put everybody at risk?

I don't have any data to show that 65 is safer than 75, or to show that 75 is safer than 65. I don't know if speed limits are based on any real safety data. But I'm pretty sure that your rationalization is not. This is my little (misguided) campaign to combat that argument. Even if 95% of the population embrace it as a plausible excuse for breaking rules and to malign rule-keepers.