The only way this problem (which doesn't seem widespread like on other airlines) is to get enough attention at the top that they make a clear directive to the agents that this is completely unacceptable.
I agree that the issues should be raised at the top. (Agreed in that just raising the issues with regular US customer service does no good.)
I have seen gate agents (at GSP) process standbys for other crew members (who seem remarkably friendly with the gate agents, as if they're already good friends) and let planes take off with empty seats, while the standby list has plenty of revenue customers on it (who aren't processed).
And when I raised the issue with US customer service, giving details about what happened, the letter that I got back indicated that the person in customer service had no idea about what US's standby policies are. (The letter included generic language, basically copied from US's website, stating that you can move up to an earlier flight for $75 or go standby if a seat cannot be confirmed.)
Thus raising these issues with regular customer service may do no good at all.