McDonalds can't set prices, the market does. McDonalds doesn't create more dollars, the Federal Reserve does. Thank you, McDonalds, for your better-than-gas-station restrooms, and for adapting to the changing conditions that are outside your control. The same is true for other food providers. 

 McD's is the market leader by far. They can and do set prices, even when inflation was low. 

 They can only "set" prices within a market-set bargaining range. Otherwise why wouldn't they just set the Big Mac price to 1 billion dollars each?