This is a good questions and one that faces many children all over the country. The decision to put children in remedial classes varies from state-to-state, and district-to-district.
The problem is that the schools are responsible for teaching your child. The way the schools are evaluated on this is, is by test scores. The school needs to prove that they are giving any child who is below level (based on standardized test scores) additional help.
It is a catch 22 for both the school and the students. I know it's not the answer you want, but hopefully you can see if from the school's point of view.
This type of scenario is often confusing to parents and students. What strikes me is placement in remedial classes- were you aware your child was struggling in school? If not you need to meet with your child's teachers. Good luck.