What I have seen is that many teachers have little choice but to ignore 90% of their students, and just focus on the one kid with special needs. I would say that a mainstream class in a public school cannot possibly give these kids what they need. Therefore, when the teacher ignores 90% of the class so that she can focus on one kid with special needs, then 100% of the students are short-changed (at great financial cost, too).
I'd like to see vouchers in place, so that 90% of the kids can go to private schools. The 10% of the students with special needs should go to government schools where everyone on staff is trained to work with special needs kids. I believe it would be cheaper and all the kids would be better off.
We have a couple of small districts in the foothills of Colorado where the parents of special education kids sued and won to send their kids to schools out of state. The school district still has to pay the cost for the kids which I think was about 50-100k a year.
Here in Texas they have taken all of the Special Ed students and put them into regular classrooms. Having taught Special Ed, I am now retired, I thought this was one of the most ridiculous things I've ever seen in Education. I had students who were so severly retarded they could not tie their own shoes and had to have a personal assistant follow them all over the school. This student wasn't teachable, yet he was in public school. At least he was in a group of students who were all retarded and not in the regular classroom where he sticks out like a sore thumb, and has no earthly idea what is going on. I pity the teacher or teachers who have to deal with this new classroom setup. I am for homogeneous groupings. Another social experiment in Education, and you wonder why Johnny can't read.
I have a friend who teaches drama at a public high school. She confirmed to me that there are many more SpecEd kids. She said they are automatically placed into her play production classes...even kids who cannot speak! She has to somehow find roles for these kids in the school plays. She said it's a huge challenge for everyone and lowers the standards enormously.