You never mentioned the word "fair" once. You asked why they leave them up. We have answered the question several times.
They don't know, don't care, or admin didn't do anything about it.
Your entire post is directed at the wrong party. The providers didn't write or ask for the fake reviews you are referring to, therefore it's not their responsibility to have them removed. Your anger at the situation should be directed at the guys writing the fake reviews.