This sounds like what goes on in our district regarding IEPs or 504's for special ed students. They don't want to write them, don't follow them, and do the bare minimum they can get away with. We don't have IEPs for gifted. We ended up finding a school with a "unique" format that allows for acceleration (basically team teaching based on ability rather than a traditional format where a kid is with the same teacher all day). They schedule certain subjects, like math, at the same time everyday so they can easily move kids to higher level grades if necessary. Until we got to this school it was hopeless. The district did have a magnet type program for highly gifted kids in 4th-6th grade but it was very disorganized and I couldn't really figure out what DD was doing there.
I doubt you are going to be able to get classroom teachers to differentiate the work the way it needs to be done, so I would push for subject acceleration and the school allowing him to attend higher level classes for certain subjects. This has worked well for DS with math (he goes up 3 grade levels, then comes back for the rest of the day). He is very bored in terms of social studies/science, but at least not forced to do math that he learned years ago.
