Presumably if the meat packers also raise wages to keep up with inflation, they will have to charge McDonald’s higher prices for patties. Similarly for lettuce growers, beverage bottlers, etc. All these would put small amounts of pressure on the price of a burger. If the ultimate price ends up going from 2$ to 3$, suddenly the 10$ to 15$ wage hike doesn’t mean anything (except for people who didn’t get the wage hike in the first place).