“Or, as in Roswell, two or three collided.”
you’d think such advanced civilizations would have solved the collision problem by now ... heck, with all the work being done on self-driving cars, WE humans might even be able to solve it in OUR lifetime! ... [i suppose at that point, we should benevolently offer our advanced anti-collision technology to any and all space aliens that want it]
Well, heck, you are the 101th genius who has suggested that line here lately.
Maybe they are much like Trump; Trump being the first leader who is not perfect in world history. They somehow got here and were not actually perfect.
Haven’t you heard; “Trump is not perfect, but I will vote for him.”? The ones who say that are, themselves, perfect.