Why do we have speed limits on limited access interstate highways in the United States when Germany does not?

Seriously, the United States is supposedly the "land of the free". Well, I for one ain't buying it. For example, how in the h*ll do law enforcement officers figure that driving 85 MPH on the interstate in middle of nowhere Kansas is somehow "unsafe"? Why can't we Americans be sensible like the Germans and have no speed limits on the interstate highways where it can be safely done? I can understand having speed limits on the interstates that go through major cities and whatnot, but having a 70 MPH speed limit through Kansas or Missouri is just plain stupid in my opinion. The only downside to not having rural interstate speed limits would be the fact that alot of state troopers would be out of jobs and the individual states would lose alot of money in "speeding" ticket revenue. Furthermore, the car insurance industry would be PO'd because they wouldn't have an excuse to raise someone's rates due to these "speeding" tickets and would lose revenue. Don't get me wrong, I'm all for common sense laws such as laws against DUI, robbery, etc., but I don't understand how a supposedly "free" country like the U.S. interferes so much with its citizens on the pettiest of issues. I think that Americans need to learn to lighten up and not be so uptight. BTW, you can even buy and own firearms in Germany contrary to the belief of many Americans.