I don't understand why some CHs are allowed to give feedback to only certain people who may well have done a good job.
Well, Skinny1, I have to agree it sure is frustrating not getting something in return for the hard work we put into things. However, it's not the case that contest holders are "allowed" to be selective about feedback. The rules stipulate that every entry gets some sort of feedback. And, if after seven days some entry still has none, the contest is suspended and the CH is notified. Failure to rectify the situation results on permanent closure of the contest. The problem comes when a contest is shorter than seven days. I suppose there's not much one can do there. Hopefully this is something the admins and moddys are looking into. Cheers.
There is something being done about it. In the next version of the contest system, you will be able to look up CH's past histories before you ever enter their contests. Also, CHs that abandon contests will not be able to start new ones.