True. We haven't confirmed a single other one yet, which is why actually finding one will be probably the most significant discovery humans ever make.
But I would imagine that an interstellar civilization that has discovered thousands of life-bearing planets would start to develop some criteria about what type of life is interesting or not. It could just be that nothing on Earth meets the criteria to be interesting.
But I would imagine that an interstellar civilization that has discovered thousands of life-bearing planets would start to develop some criteria about what type of life is interesting or not. It could just be that nothing on Earth meets the criteria to be interesting.