It should be, but there's the problem of demand. Somebody has to be motivated to do it, meaning that they are probably equally passionate about music and image analysis.

Also, a lot of the written stuff is handwritten, not typeset. So it's a subset of the handwriting recognition problem.

It's pretty bad for the bassist, since the bass part is usually the second to last part to be copied, meaning that the copyist was probably drunk. ;-)