No government speed limit laws or regulations would be possible in a truly free society.
Private property owners can set whatever rules they want (as long as those rules are disclosed in advance, and cannot harm your life, liberty, or property without your consent). With competing privatized highways, whenever I have a choice, I'll favor routes where you can go reasonably fast, and so will most other people. What "reasonably fast" is will mean different things to different people, mostly depending to the hotness of your car, so privately controlled speed limits could also be a boost for the automotive industry. Another benefit is that it will get all them onramp-clogging grannies onto different roads than them 130+ MPH hotrod nuts.
I predict that on most privately-owned freeways, the speed limits will be flexible, depending on each driver's "speed karma". You must have insurance and no at-fault accidents in last X years where speeding was a factor to go over Y MPH or even get on the fast lane(s). I don't mind private companies using high-tech methods to ID all cars on their road, as long as the government isn't involved. Competition and consumer activism would drive the privacy standards to where they should be.
EDIT: Yeah, yeah, I know, I expressed very similar ideas just a few posts above. Guess I forgot, and didn't notice.
They probably do fear you, rancemuhamitz, especially if you look like your avatar pic.