> So you have to pay constant attention for longer, it is tiring and a tired driver means the chances for an accident are higher.
Don't disagree with that but do disagree with your line of reasoning. Driving the same speed, for hours, on cruise, makes zoning out way more easy. And at 130kmh+ things happen way faster and so you have to be extra engaged to void potentially deadly crashes.
As I said in another comment, they're less dangerous because of the way the traffic works but if you look at the numbers, the fatalities to crashes ratio isn't all that different between highways and country roads.
Volume is obviously different, but there's also fewer people driving on highways than regular roads.
Still, I'd not say that driving on highways is safe while driving on country roads is dangerous. They're both dangerous, just for different reasons.