Certain people are licensed by BE such as the Course Designer, the Steward, the Course Builder, and they all get BE training in order to qualify. I don’t know about payment but I presume they get something. Fence judges, ring stewards, crossing stewards, pole pickers, stable managers, person who sets up all the dressage arenas, all do it for the love of the sport. But the Fence Judges do have a full briefing before each Event.
Blenheim Palace 4*, when run by BE, had a full time boss person and her two assistants. Everyone one else in the 350+ roles were unpaid volunteers.