I wasn't making any comment about the predictability of humans. However there have been plenty of studies that have proven humans are indeed predictable. If we weren't then dark UI patterns for email sign ups, cookie consent pop ups, and so on wouldn't work. The reason UI can be tuned for "evil" is precisely because of our predictability. But this is a psychological point and thus tangential from the discussion :)

To come back on topic. I wasn't saying hardware is unpredictable per se -- just that it often behaves unpredictably. And I say that because there are a set of expectations which, in reality, hardware doesn't always follow.

However the predictability of humans vs hardware is a somewhat moot point because that's only part of the story for why writing hardware-interfacing code is harder than human interfaces. I did discuss cover a few of those other reasons too but you seem fixated on the predictability of the interfaces.