OP: I would bring along a short note from your child's pediatrician stating that your child has Autism, and has trouble with "X" ("X" possibly being "waiting in enclosed dark spaces", "being in close contact with large crowds of people", "personal space issues", "noise/light sensitivities"...or whatever is your child's BIGGEST hurdle related DIRECTLY to the experience of being in a theme park environment and waiting for lines/attractions.) This will help the CM's issue the proper type of GAC.
I am the parent of a child with Autism. He is almost 5 and has been going to
Disneyland since he was about 4 months old (WAY before he had an Autism Dx).
We have NEVER used a GAC, partially because I didn't find out about it until about a year and a half ago, but also because I just TAUGHT my child how to wait in lines. There are other places in our daily life that we have to wait that don't have GAC's...(supermarket, Target, appointments, etc.).
I certainly understand the need for GAC's in general. I don't advocate them, however, for EVERYONE and their mom who has ANY disability. That's where it becomes abuse.
I have talked to MANY moms of other children with Autism (classmates of my son at his preschool) who brag about how "awesome" it is to have the GAC at Disneyland so they don't have to wait in line. And, from further conversation with these parents, I know for a fact that they are abusing the system...and that their children CAN wait in lines, and don't have any reason to really be using the GAC's. I know their kids...it's sad to me that, rather than using DL as a way to teach important life skills to their children, so many parents just take the "easy out" with the GAC.
Sure, sometimes it's hard to wait. And if my child starts acting up in line, you know what we do? WE GET OUT OF THE LINE! And, if the line is too long? WE DON'T GET IN IT. And we choose another ride instead. Just like we would if our child was NT...