It is against the law to speed. Most of the population does it. You can drive safely and speed. I don't buy the fact that in a 70 mph speed limit area that a driver doing 70 is safe and 71 is being unsafe. If that was the case police would pull people over for doing 1 over. I have never heard of anyone being pulled over for doing less than 5 or more over. That tells me that the police must feel that a few over is safe.
I have seen many people that drive the speed limit that are unsafe. They have no awareness of what is going on around them and don't plan ahead when driving. It's obvious watching them.