Too dangerous in America = too complicated for stupid people in America
Too scary for people from Australia, too, especially the one I encountered on a curved bridge with limited vision around the curve.
We have three lane roads, too, but they don't rely upon the good sense of motorists.
They are, in turn, two lanes one way, & one the other, & the lane markings reflect this.
That way, both directions have an opportunity to pass safely.
Old style 2 lane roads have "bulges" where such sections are used, with each way getting its own "bulge".
Any other passing is strictly policed.
You can't predict morons though, quite a few times, I've encountered halfwits passing road trains in places where the safe passing distance is rapidly diminishing.
The funny thing is, they're usually not driving Beemers, Mercedes, big V8s, etc.
No, these budding racing drivers are often driving delivery vans & the like, in the Toyota Hi Ace class.
Not that I'm dissing Hi Aces, they are quite good for long distance trips, but:-
"A man (& a van) should know his limitations,"