But then what do you need laws for? The driver already has the incentive to balance their own safety against their other interests. Laws are only needed to prevent someone from imposing an externality on an unconsenting third party.
I'm not too familiar with US or European highways.
What I am familiar with is lots of curves, inclines, declines. The kind of road where a loaded truck going the limit easily flips into the cliff to the side on the slightest error.
See, that's a little bit of a problem if you're trying to make a point about why US cargo trucks should have speed limiters then, because: none of those things apply to US highways.
US highways are (by design) very straight, very flat, and very long. And on the rare occasion they're not, there are already speed limits in place.