A teacher in high school once said when it comes to alien life form. If highly evovled life live on other planets. It is either common or rare. If it was common wed know about that civilization, if it was rare we wouldnt about supposed advanced civilization and they wouldnt know about us.
Finding earth in the galaxy is essentialy finding a small hair pin needle in a very big haystack. That distance in that haystack is enormous. It is hard to envision any craft traveling many lightyears through the universe without somehow severely altering the laws of physics.