[mdip]

In general, I agree with your points. In Michigan, with a few exceptions (freeway design limitations/residential roads), the speed limit is supposed to be set at (I think) the 85th percentile. Effectively -- county/city/township road speeds are set at the speed most drivers are driving. We're strictly set at 70 MPH on freeways with few exceptions for specific freeways not designed to safely travel at those speeds and the limit will soon be raised to 85 MPH for rural freeways. I've watched the city roads increase speed limits over the last 10 years where I live, which is a busy metropolitan area. It's really quite nice since it's less chaotic when everyone is traveling at around the same speeds on the roads. And it has reduced speeding.

I do not speed -- I had received a ticket in my 20s that raised my insurance rates so much that I just don't accept the risk. There's a road near my house that practically everyone drove 50 MPH down despite a 40 MPH posted speed limit. They raised it two years ago to 55 MPH after a traffic survey and as a result, I am no longer passed when I drive at the posted speed. It's an anecdotal account, but I'm on that road a few times a day many days and it's a stark difference. When the speed limit is set to what people drive, most people stop speeding.

That said, residential roads at 25 MPH is a rule that the 85th percentile rule doesn't apply to -- for good reason. Parked cars where pedestrians emerge, roads that are not maintained well or cleared for snow/ice, and children who do not have the proper sense to not "run off into the street chasing a ball" all make speeding in subdivisions dangerous.