Judges in many parts of the United States are elected, so there is no particular guarantee they have studied anything.
Judges are lawyers, but the approval process and performance of judges who are willing to follow the rule of law and rule in ways that aren't simply in line with "nepotism" is significant.
Even existing supreme court justices appointed have not taken actions that the folks who appointed / approved them might wish... that's a good thing.
I don't think that's completely accurate. It's very much party politics at the local level. Party hacks are rewarded. (Which may look like friends and family, but party discipline is highly enforced AFAIK)