Because they are all in the same field.

Lawyers can be judges one day and judges were lawyers and can be lawyers again. They may come from the same school or even the same class, have the same professor, know the same people, join in the same golf club., etc. Or they may just have prior working relationship and have established mutual respect. Well, you are just an nobody. I am not saying they would put themselves out as to be corrupted or irresponsible, but definitely those delicate things matter in cases where moving left or right one inch would make a world of difference.