I have worked at a utility where the supervisors were all buddies of the site coordinator. All except one was a good supervisor and it didn't take long for him to be replaced.
I was made a supervisor at the site mostly because of my career before being an HP. I took it very seriously and did my best to take care of the techs and their needs. I always thought that if you did the techs right, they would know and do you right. My first commitment was to the techs and not the house.
I remember being involved where the NRC tried to bribe me after they got caught doing the wrong thing. They screwed up and tried to blame it on one of the rovers. I turned it around and challenged them to make something of it.
Ok, enough patting myself on the back.
But having over 20 years in the business, I have found that the supervisors and site coordinators are hand picked by the Contract Company and not the utility. The utility really doesn't care unless they do something that shows up the utility. Even then it it hard to replace them.
If the outage went ok, the RPM and the management lets it go.
Ok again, we all know supervisors and site people that are as smart as a box of rocks. BUT they are there year after year.
It is just the business. The techs know who is good and watch their backs.