Same in higher (university-level) education in the UK due to legislation. It forces institutions not to become closed shops. In many cases the institution has a

Same in higher (university-level) education in the UK due to legislation. It forces institutions not to become closed shops. In many cases the institution has a preferred internal candidate, but forcing them to open it up at least gets external people a foot in the door. In many cases the internal candidate is the best for the job because they know the institution well so they don't need to be brought up to speed on many systems and are familiar with its pedagogical philosophy, although there are obvious downsides where a department can become stagnant if it's always the internal candidate, like a kind of academic inbreeding. But I know of at least two cases where the external candidate won despite there being a preferred internal candidate because the external people were so much more suited to the role.