Yes. They do. I've already seen rangers spawning in Lone-lands. Thrice. First time, it was a grup of 5 rangers and one outriders. Second time there were just two. Third time it was in Eriador: eight rangers near the great east road (I looked for a tower if they ever came from it, but it wasn't). They just spawn at a very low rate. They are just very, very, VERY rare. A bit like gondorian renegade in Umbar. You must walk hours and hours in the biome to see them spawn. And even sometimes, it doesn't suffice.
But it's a good thing, I think, they spawn rarely. Because I remember they spawned at a rather hightrate in elder versions. And travelling in the wild as an evil player was almost impossible without meeting one of these guys. Furthermore, according to the lore, dunedain are few. It is logic so they cannot be seen everywhere.