The distance it takes to reduce your speed or come to a stop at 71 mph versus 41 mph makes your argument invalid.
Maybe so, but I would like to point out that most places that have a 55 mph or greater limit are limited access highways without intersections, driveways, school cross walks, etc. It’s not often you have to come to a complete stop. 16 mph over the limit on a limited access highway is no where near as bad as doing it in a 25 mph zone, which is typically in a residential area.
Increasing speed from 25 to 40 nearly doubles the distance need to stop from 85 ft to 164 feet.
Increasing speed from 55 to 70 only increases the distance need to stop 46% instead of 93%, from 265 ft to 388 feet.
http://www.csgnetwork.com/stopdistinfo.html