They aren’t. They’re agreements within chains, contained in the contract the franchisee makes with the franchisor.
To keep labour costs low within the franchise within a given region (for the franchisee) and to keep the chain’s advertised prices low (for the franchisor).
Let’s say there are three Arby’s in a particular county: A, B, and C, each owned by a different franchisee. The agreement is meant to make sure that the owner of Arby’s franchise A can’t lure an experienced employee from Arby’s franchise B or C by offering him a higher hourly wage. If the employee tries to move from C to A on his own, his application is likely to be tossed in the trash rather than the franchisee risking being in breach of the clause.
So basically if you work at Arby’s A in that county you’re their serf. You can move to the McDonalds down the street but chances are you’ll be making the same hourly wage because all the county’s franchisees from all the county’s chains know each-other and chat informally at the golf club.
