Why it's hard for food giant to change

McDonald's is an industrial wonder. It's the biggest restaurant chain in the world, measured by sales, with some 14,000 locations in the United States and 36,000 globally. That's the problem. Executives proudly refer to "the system", which guarantees that its French fries will be the same size everywhere and cooked for exactly the same amount of time; its burgers will be the same thickness and have the same taste; and its liquid eggs will be pre-cooked, folded, and flash-frozen by its suppliers before they become part of a bacon, egg and cheese biscuit.

McDonald's doesn't operate on gut feelings, or instincts, or even experience. It uses focus groups. It finds test markets. It runs the numbers. Too much change can break the system. And if there's ever a conflict, the system always wins.

Don Thompson had two-and-a-half years as chief executive to try to make McDonald's more relevant to US eaters. It took McDonald's two years to develop a simple chicken McWrap. And that's only when it was clear that Chipotle - once part of McDonald's - and Five Guys and Shake Shack and Subway were stealing younger customers with fresher, seemingly healthy foods that could be made to order.