It's shaping up to be a battle over fast-food workers. Burrito chain Chipotle Mexican Grill threw its hat in the ring on Monday, announcing that it plans to hire 20,000 more employees as fast-food chains scramble to reopen dining rooms now that the health crisis has eased. In order to lure workers to its restaurants, Chipotle is bumping-up its average hourly wage to $15 by the end of June, but pay could go as high as $18 an hour.In addition, Chipotle is offering a $200 employee referral bonus for crew members and $750 for apprentices or general managers. It is not alone in its efforts. Several U.S. chains, including the biggest of them all, McDonald's, are adding benefits or running hiring events in attempt to lure new employees. Some business leaders say they are facing a worker shortage, even though there are still millions of Americans out of work. There is a debate over the reason why. Extra jobless benefits are being blamed for keeping lower-wage workers at home, lack of adequate child care is another factor believed to be a cause and then there are some Americans who might still feel it is not yet safe to go back to work.