One of my colleagues, who is an experienced teacher, was hired where I work. She has to take training as a “new” teacher. One aspect of the training is to discuss students with special needs. The special needs students discussed in one class was under-prepared students. That isn’t all of them, but it is a lot of them.
Math is very cumulative, and students don’t seem to realize that what they are taught in earlier can’t be forgotten after the final exam, unless they don’t take any more math courses. Under-prepared students are an increasing problem. But assuming they have special needs suggests that they constitute a minority of the students. Sadly, they come close to being the majority.