Many of the Renaissance Festivals in the US are run by a professional festival company that produces these events throughout the country. There used to be 3 or 4 main companies that provided the whole show - all the performers, some of the staff, the set-up and tear down of the festival, etc. - for a percentage of the gate. They hire some local performers and staff, and but the more elaborate performers, the PR people, the truck drivers that move them from city to city - they all work for the Ren Fest company. One of the biggest ones is called Mid-America Festivals, and they produce not only Renaissance Festivals, but also Haunted Houses, promote some music festivals and rock concerts, too. http://www.mafestivals.com/

Those companies usually have a contract for the Festival every year, and if they do a good job, they keep their contract for the next year. That's why you see the same shows, the same performers, etc. They are paid professionals who go from city to city, like the touring group of a Broadway play.