Well, I sent the photos to Canon and here is the response I get:
We appreciate your continued correspondence.
Of the images you sent, all but the 19-pt AF seems to be as accurate as I would expect. However, this particular example I can understand. The camera is actually choosing to use all 19 points to determine the right place to focus in this example. Also, trying to focus such a broad area of a white piece of paper with lines on it against a white background can confuse the focusing system in the camera. These sorts of tests are not guaranteed to work properly and real world shooting conditions are always the better way to determine how the camera is really performing. There are times when letting the camera try to choose from all 19 points can reduce accuracy, so choosing to focus on a single point in this case was the best decision.
AF (Auto Focus) can fail to achieve correct focus on certain subjects such as the following:
Low-contrast subjects. (ex. blue sky, solid-color walls)
Subjects in low light.
Extremely backlit reflective subjects. (ex. car with a reflective body)
Overlapping near and far objects. (ex. animal in a cage)
Subjects with repeating patterns
Competing objects and distances
Please let us know if we can be of any further assistance. Thank you for choosing Canon.
I find the whole response unacceptable. He somehow thinks the center zone AF is "what he would expect" yet the 19 point AF is not, and yet both are equally as fuzzy. He rationalizes the poor 19 point AF performance by saying that it was using all 19 points, but all 19 points were in the same plane so how does that explain anything? I especially find his reminder that "real world shooting conditions are always the better way to determine how the camera is really performing" to be annoying. As I reminded him in my reply, it was precisely real world shooting conditions that started me on this in the first place. I have family photos from vacation, shot in good light on a tripod, that had such poor focus I immediately noticed it when I was processing them. I have photos from previous years, same conditions, same location, same lens, shot on my old 30D that are better.
But what can I do now?