Generally speaking, trial by jury is a concept spread by British imperialism. Thus the UK, Australia, Hong Kong, the United States and others have juries, while India and Singapore used to. Much of Europe has them for certain types of crimes or for a certain portion of a trial, but it seems the Netherlands is an exception. See here for the history and prevalence of jury trial systems.
Note that juries are almost always part of the legal system of countries with common law, but not necessarily those with entirely civil law (which includes the Netherlands).
Actually, een jury bij een wedstrijd is een groep van personen, so a contest judge (singular) would have to be a jurylid (juror) ...always assuming that (s)he had companions in this role. Are there no competition judges who work alone in the Netherlands? Might the term beoordelaar perhaps cover this function?