I was waiting for JD to post...
...I was hoping for a professional viewpoint.
First of all, I am not not criticizing teachers in any way shape or form. I having the highest regard for teachers. I have seen some of these little monsters in my daughters High School, and can only imagine the difficulties you must face every day. Personally, I'd have killed off about half of them. (good thing I'm not a teacher).
Regarding the 18 year old girl in your example...why was she allowed to have progressed so far through the system as to be a senior on a 3rd and 5th grade level? Shouldn't this have been identified long before now? And if it was, why weren't corrective measures put into place at that time? What broke down here?
What are your feelings on the "No Child Left Behind" theory of education? Or is that just a Nebraska thing? I don't know. I have seen entire classrooms stagnating for weeks because one or two of the kids need extra help with (or just don't give a rats ass about) the subject matter.