Honestly I think its only people who don't know how to drive, don't understand and maintain their cars, and don't know how to handle them that think a few mph over the limit is a grievous offense.
My alertness combined with my properly maintained car and tires is going to stop shorter at 27mph than trashed cars with bad tires and stupid drivers texting while driving at 23mph.
I know what size and type of tires I have off the top of my head, I know the tire pressure of each tire, and I know my stopping distance/time for dry and wet at 20 40 and 60 mph.
I'm far more concerned with whats on the road than any of you obviously...who simply stare at their cluster gauge (or the radar gun your holding out the window since your state didn't require a speedometer) to make sure they maintain exactly the speed limit. Even if they don't know how accurate their gauge is. And then get pulled over because the gauge the cop was using said you were going 2mph over anyway.
Who's at fault? Obviously cops are never wrong.
Me I'll simply drive safely at all times and try my best to maintain a safe and proper speed, even if I sometimes exceed the speed by a small amount due to any one of many factors.
Edit:
And I have actually independently had my reaction time and other aspects tested at a professional driving facility.
I'm proud to actually be one of the few good drivers on the road. I actually know it when I say it.
Never an accident or moving ticket. Never pulled over and no close calls. I have about 320k miles experience so far.
My first and only ticket ever was for an expired license vehicle I had just moved (with a trip permit) and parked on a city street.
That was a mistake on my part for various reasons, live and learn, but I went down paid the ticket and had it licensed the next day.