Why Do Advanced Students Have Such a Hard Time Succeeding?

I rarely write about personal things on this blog, and instead try to stay somewhat objective.  But today I shall make a small exception due to having a discussion with a friend who made some valid points.  I'd be curious to get some feedback, because this is something that has run through my mind many times.

I have the dubious pleasure of being the parent of a gifted child, one who is in fact considered to be twice-exceptional.  This means that whilst there is significant advanced capabilities in some areas, there are also delays in others.  So they have advanced needs and an IEP.

So onto the conversation; I was complaining that the school should be happy to have gifted students, and I didn't understand their reluctance to help an advanced student the opportunity to succeed as it reflects well on the school.  Here are the reasons that schools might not want to help your gifted (NOT high achiever, Type A; know the difference!) child.  This doesn't go into the whole problem about teachers not being sufficiently trained to recognise giftedness (although in the context of this post, thats very convenient too), but more goes to addressing the problems gifted kids have when they KNOW they have a gifted kid in their class.

1. Budget. Schools are beaten into keeping budgets. Kids with differences cost time and money, unless they're (financially beneficial?) disabilities which do bring in extra funding.
2. Testing. Once a child isn't failing, they don't matter. Kids that don't function well bring in more resources. Once they hit average, they do not bring anything more than base funding in. No state gives funding for helping gifted, only to bring the unsuccessful up kids up to the "accepted standard".  So why give extra help to the two kids that get 100% in all of the tests, since they help to raise the average score in your class, moving them on would simply impact the average score.  They don't need help they're doing just fine.  NCLB specifically discriminates against gifted kids.
3. Teachers are humans. They don't, except in outside cases, want to do extra work for no extra money, sure there are the "Mother Theresa's" of teaching who would teach for free under any circumstances just to help the kids, but by and large, they want to go home and get their dinner, mark their papers and wash their kid's karate uniform for tomorrow.  For the most part human nature is such that people don't dedicate the majority their mental bandwidth figuring out how they can do a better job each day, these days a mental dialogue looks more like "oh geez!! I'm late paying the water bill, Johnny has a sleep over in two days and I need to get food in.  Lisa has a cold but still wants to go to soccer practice, do I keep her home? John is on a work trip next week and I have the kids on my own, that's going to be rough.  I really need to get my hair cut..... "  and so on.
4. Teach to Test Recognition. Again a teacher is human, and humans in general crave praise and recognition. A teachers performance is assessed based on the grades of their students, the kids get great grades the teacher gets a pat on the back.  All of the kids in the class pass with top scores, the teacher gets recognised, perhaps awarded, and honoured. This looks great on a resume.  So as a teacher it's only natural that you want to do the "best job" you can do. That job no longer includes teaching kids, it's almost entirely based on tracking metrics via testing, so obviously the teacher wants the best little tester that he or she could have. 
5. Administration.  A school has enough problems keeping on top of the mandatory paperwork as it is.  A child that doesn't fit the norm surely generates more admin, more paperwork, more effort on the part of the school administration.  Conforming to average is good for the administration.

I could have all, or part of this entirely wrong, and if that's the case, I look forward to people providing me reasons as to why kids like mine and my friends' are left to languish in classes that are at least one or two grades below where they need to be learning?