Earlier quoted context omitted.
Those houses are generally located far away from the road (farm houses) or are in some other way separated from the road way. If it’s a rural highway and houses are near the road, it typically results in a speed zone, even in desolate Nevada.
That's not true everywhere. My wife's parents live in rural Iowa on a highway that has a 45 mph speed limit. Their home is part of a small cluster of homes and their mailbox is across the road, similar to the circumstances in the OP story.
Regardless, living on a highway is not prime real estate.