"Some of fast-food’s biggest names, including Burger King, Carl’s Jr., Pizza Hut and, until recently, McDonald’s, prohibited franchisees from hiring workers away from one another"

NYT:

The restrictions do not appear in a contract that employees sign, or even see. They are typically included in a paragraph buried in lengthy contracts that owners of fast-food outlets sign with corporate headquarters.

Yet the provisions can keep employees tied to one spot, unable to switch jobs or negotiate higher pay. A lack of worker mobility has long been viewed as contributing to wage stagnation because switching jobs is one of the most reliable ways to get a raise.

Defenders of the practice argue that the restaurants spend time and money training workers and want to protect their investment.