I don't have time to write out all the reasoning I could try to apply to this right now. I might try to come back to it this evening.
I will say that, as a person that has written software to build systems, that understanding some of the underlying details of how something works has often been helpful in understanding why things do what they do. All abstractions leak, as it were, and there's a cost when they do.
I suspect that getting to the right answer by just reasoning, without actually breaking down how the scanning mechanism works, is potentially building on faulty assumptions, but I don't have the time to work the details on that now.
Something that may be unrelated, but comes to mind: Many people, myself included, scan documents by using a cell phone camera, which would change the result here, by changing how the scanner works. But perhaps that would show up in the way the question is phrased.
Definitely that sort of brain tickler that is probably more interesting to think about than it might have any right to be.