It is SCARY seeing a vehicle heading toward you on a freeway, it has happened to me.
And me. About a year ago.
Four-lane divided highway with *very* wide grassy area between N and S lanes. Heavy fog. I am driving fairly slowly in rightmost lane due to poor visibility when Wooosh! someone comes by me in the other lane going the wrong way! By the time that car registered in my brain it was almost on me and then gone behind me before I had *any* chance to react. Took me a few more seconds to even realize something wasn't right!
I can see how it happened. Someone not familiar with the road came in from a side road (there were at-grade crossings with only stop signs) and seeing only the one paved area simply turned onto it and kept the the right, little knowing he was about 50 yards short of the *real* right-hand lanes for traffic in his direction.