Where I live it's like NASCAR compared to the posted speed limits. The true cause to all of it is the go with the flow policy that's been socially accepted. A phenomenon that I've noticed is that whenever the police are on the road the speeders slow down. However, if the police break the speed limit as well the speeders match it, but don't pass it. Zero self control unless the parent is around. That's what it reminds me of.
Common excuses that I've read and heard are things like: I'm late, I didn't notice, and the crowd favorite, I was going with the flow of traffic. Anyone like myself who actually follows the speed limits (even when alone on the road) should stand strong and continue being independent, responsible adults. Anyone who does the opposite should do research on all the cons of speeding and do the math regarding how much it actually puts you ahead of the non-speeders. A few cons off the top of my head would be increased gas used, increased braking, and reckless endangerment of human life. Think for yourselves people or continue thinking for yourselves.