>>509353580 (OP)Why do human scientists quietly observe wild animals on the African Savana from hidden blinds? Why do those same scientists occasionally tranq, capture, measure, test those animals, take biological samples from those animals, then release those animals back into the wild? Why do scientists go into the deep jungle to take plant specimens and catalog new species.
We do that kind of shit because we are scientifically curious, because we want to expand our knowledge of the biological world, because we want to monitor and understand (maybe even preserve) unique ecosystems, and because maybe we'll stumble upon something that will lead to a cure for cancer. I believe there are aliens out there, they can travel between the stars, they do sometimes visit Earth, but they see us the same way we see interesting but dangerous animals in some far off nature preserve. They study us from a distance, from a reasonable amount of cover, but they are never going to make open contact with us for the same reason the US is never going to open official diplomatic relations with the chimps living in the Congo or a pride of lions.
We will never be allowed to travel between the stars ourselves, not because Earth is a prison, but because they don't want a bunch of wild, unpredictable, dangerous animals roaming their neighborhoods.