Special Ed teachers may have the same students for several years. Depending on the needs of the students, they may not see a lot of progress, and can become discouraged about their jobs.
Of course some students with special needs are "mainstreamed." Some are integrated in regular classes, and the teachers working with them function a lot like teacher's aides with the other kids in the same classes. Others only go to the Special Ed teacher for part of the school day.
Often the parents of kids with special needs seem to expect their teachers to work miracles and teach their children to function at the same level as other kids the same age. Others are in denial that their children have special needs at all. Either way, parents can sometimes give the teachers a hard time.
Special Ed teachers have important, but difficult jobs. If you know any, please let them know you appreciate what they do.