Ford has been, however, sued multiple times over the Magnuson-Moss Warranty Act of 1975, for trying to void the warranty if you made aftermarket changes. Because you bought the Ford and the laws say it's yours, you are free to rip out the Ford engine and put in a Honda engine if you so please. (Emissions laws notwithstanding.) If Ford was saying you cannot tear out the engine on a car you own and put in a different one, and they welded the hood shut, then it would be a better comparison. Neither Ford nor Apple would be so foolish though. It's just that the metaphorical hood welds in the iPhone's case havent been broken recently.