The Andante from Bach's Italian Concerto is an effective example of rubato embedded in the score.
How so? If rubato refers to the individual performer's robbing of tempo in certain places, and catching it up in other places, to suit his or her musical intentions, then it seems to me that by definition it isn't part of the score but something that the individual performer adds. I think the Bach Andante from the Italian Concerto could
be played exactly
in time just like any other work in the entire musical literature could be (subject to human error for not having metronomes in our heads
), but I agree that that would be terribly boring.
You know the finger and the moon thing... Rubato is performance related, of course, but the premise of rubato
(out of sync RH to LH, to put it simple) are in countless examples in the music writing. If you play the Andante from the Italian Concerto "in time" (like a MIDI sequencer, to make it clear), you have plenty of "out of sync" moments. All the music is like that, most of the times. So it's simply not true that "things that are out of sync (melody to harmony) sound terrible.", because they are most of the times. Now, rubato is just the same thing, only with smaller values and undeterminable with accuracy, and that the composer can't put into writing without making the score look a mess. I'm oversimplifying but you're smart and I'm sure you got the point.
The fact that most of you seem not to manage to conceive such a possibility is probably because that
kind of rubato is extinct. In a post of mine above there's a link to Saint-Saens playing is Valse nonchalante and where I pointed to a couple of moments of Saint-Saens's rubato. I don't know if Chopin's rubato was similar to SS's, but for sure today we don't have any kind of rubato anymore.