The idea that judges shouldn’t be elected is deeply rooted in the reactionary ideology of an aristocracy that believed the masses shouldn’t be trusted with any decisions that actually matter and should be regarded with suspicion instead of trusted with decisions.
Judges shouldnt be elected for the same reasons surgeons shouldnt be elected.
Legislators are there to directly reflect the opinions and interests of their constituents, judges are there to have expert knowledge of the law and how it applies to each case uniquely. The first needs some form of democratic mechanism to ensure that they represent people’s current opinions, the later needs a meritocratic mechanism to ensure they are experts in the correct fields.
If judges were the only element of a court I would agree that it would be problematic to have no democratic input, but in common law systems at least that element is represented by juries who are the most powerful element of a court case as they are unchallengable arbiters of fact and drawn through sortition which is even more democratic than election.