Not just the quality of the scanner - The scanned copy will likely be faded. Ideally, they would compose multiple scans to find a better one, but that has accuracy errors, too.
To use an analogy, even if rolling 1d10, it takes a *lot* of rolls before you really get close to 95% accuracy on the mathematical centerpoint of 5.5; especially when your max roll is 9.5. And at a certain point, buying more copies in order to have more data to feed into your algorithm to make the book look closer to original, not only means you have cut a sizable chunk out of your net profit, but also that it would be cheaper to hire an artist to touch up the cover.
Side note: At this point, the Sistine Chapel is about three or four "Axes of my Grandfather's" away from being painted by Michelangelo. The artist, not the ninja turtle. The distinction being, I think, that this is known and acknowledged information.
But I philosophize again. Your Wikipedia quest, should you chose to accept it, is to look up "Hill-climbing algorithms". This message will almost certainly not self-destruct in five seconds, although with quantum physics, we cannot rule out that one of your electrons comes from Alpha Centauri. Or Beta or Ceti Centauri. How come they never get mentioned?
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