You were scanning a screen, which is perfectly flat, has no crumbling and no smudges. You are using a high resolution camera close to a high resolution screen, on a relatively large QR code. You have a best case scenario, and if that's all you care about, you'll be happy with it.
For now, anyway. If you are using the same scanner implementation that the author used to check their results, then the good results you are seeing are due to the generation algorithm being tuned to work with that particular implementation. But there's no guarantee that the implementation will stay the same in some future iOS. Say Apple makes some change, to better recognise bleached codes or something, and then suddenly some of the drop shadows are interpreted as 1's instead of 0's. They could do that, because that wouldn't require changing anything for codes that follow the spec. But it might break that pretty, pretty code that you just put on a million milk cartons.
For now, anyway. If you are using the same scanner implementation that the author used to check their results, then the good results you are seeing are due to the generation algorithm being tuned to work with that particular implementation. But there's no guarantee that the implementation will stay the same in some future iOS. Say Apple makes some change, to better recognise bleached codes or something, and then suddenly some of the drop shadows are interpreted as 1's instead of 0's. They could do that, because that wouldn't require changing anything for codes that follow the spec. But it might break that pretty, pretty code that you just put on a million milk cartons.