Follow the link in my signature to get to the disABILITIES FAQs thread.
Post #6 has information about Guest Assistance Cards.
Disney does not have anything official in writing about Guest Assistance Cards, but the information in the FAQs thread about GACs was reviewed by a number of Guest Relations CMs (who actually give out the GACs) and also by attractions CMs (who actually handle the GACs).
As was pointed out, the GAC is just a tool to help CMs know what kinds of special assistance a Guest with an invisible disability needs.
If anyone visits the board Stupid Guest Tricks, they will find a pretty long thread where CMs are talking about how many guests expect GACs are front of the line passes and how frustrated they get dealing with guests who think and expect that.
As has already been posted, it is printed right on the card that it is not meant to give immediate access and they recommend getting Fastpasses if the guest wants to shorten their wait.
Recently, CMs have been reading and highlighting that information and initialing it so that it is clear the guest was given that information.
A couple of things about waits -
Most attractions have accessible (Mainstream) lines and guests who only need an accessible line (including most guests with wheelchairs and
ECVs) do not need a GAC to use the accessible lines. Those guests wilt be in the same line with other guests. There is a Guidemap for Guests with Disabilities for each park, which lists the Mobility Access. In most cases, it says, Enter through Standard Line. For attractions whit Fastpasses, it says Obtain a Disneys FASTPASS or enter through Standard Line.
GACs are for guests who have other needs that are not visible.
DisneyLAND is much different than WDW. Because Disneyland was built so long ago, many of the lines are not wheelchair accessible and cant be made accessible. The only way for some guests with disabilities to ride may be to enter thru the exit. That doesnt mean they get boarded any sooner and it is not an advantage, it is the only way they can get on.
MK at WDW has some of the same accessibility problems, although because of space most attractions are able to be made accessible through the regular line. Haunted Mansion is one that is not, but usually guests with wheelchairs or ECVs wait in line until the line is almost to the point of entering the building. At that point, there is a pull off and guests with wheelchairs and ECVs go to the exit courtyard. That does not mean they board right away. Every time we have gone, we have had to wait at the hearse (which is the pull off point) for a CM to come. Then, we join the rest of the people who are waiting in the exit courtyard to board. Someone seeing us pulled out of line at the hearse might think we are getting on ahead of them, but in actual fact, since a large batch of people enter the building at the same time for the preshow in the stretching room, the people still in line are getting on at the same time as my family. We also have to skip the stretching room because the ride is not accessible when going thru the stretching room.
When there is a pull off, it is usually close to the regular boarding area.
Misconceptions happen a lot. Because people got pulled off in some attractions other guests and even the guest with a disability assume they waited a shorter time. The last few times we rode Buzz Lightyear, we were getting into the regular line with DD in her wheelchair when a CM stopped us and sent us thru the Fastpass Line. The same thing happened to a family behind us with a child in a wheelchair. They commented how lucky they were to be able to get in without waiting (and Im sure told people later how they didnt have to wait). My family knew that the wait in the regular line was only 5 minutes at the time we were ready to enter the line - so we waited the same time we would have if we had stayed in the regular line. But, we did not have to go through all the twists and turns of the regular line (and a CM has told me that is one of the reasons they pull guests with wheelchairs and ECVs into the Fastpass line when the wait in the regular line is short - having mobility devices in the regular line slows it down).
Often guests with wheelchairs/ECVs or GACs are in a different area and may feel like they are getting in faster because they are not waiting in the line, but they are still getting into the same show as the other guests.
This happens with many shows because there are limited numbers of seats for people with special needs or they need to get them into the theater first for the safety of all guests, to get into the correct spot or to set up equipment (like reflective text devices for guests with hearing impairments).
Some shows have very limited seating for guests with wheelchairs/ECVs - for example, the Tiki Room has a very limited number of wheelchair/
ECV spots and we have gotten to a show that was only half full, but we could not see it because all the wheelchair spots were taken.
They may give a different place to wait, but the wait may be the same. In May, my mom, my youngest DD and I went to see the Fairies at MK in Toontown. We had done it before, waiting in the regular line with everyone else for 45 min to 1 hour. It was very difficult for my DD because her wheelchair kept getting bumped and jostled. And, just when we would get near to the front, guests who were in front of us would call the rest of their party and a group that had been 2 turned into 8 (mom and small kids waiting outside the line). When we went in May, I did show the CM at the entrance DDs GAC and asked if we could wait somewhere else. We were given a card with a number on; the card said that our wait would be at least 30 minutes (and the CM said it would probably be equal to the wait of guests in the line). We were shown a place with benches at the exit to wait. When the CM from the characters came to get us, Im sure that some of the people waiting in line did not know that we had been sitting there for 30 minutes. We were taken to the door where guests who have just seen the Fairies come out and Im sure that some of them thought we had just come thru the exit without waiting. We waited there for about 7 or 8 minutes. Then, we were brought one step closer and waited a few more minutes before being added as the last guests to the next grouping of guests going into see the Fairies. Im sure the guests in the grouping we were added to also thought we had just come into the exit without waiting.
But, when everything was added up, we actually ended up waiting 45 minute total. I know because I was watching the time, but my mom (who was not watching the time) was sure it was much less than that.
Because each guests needs are different, not all GACs say the same thing and not all accommodations are available at each attraction. For example, someone who has GAC because of difficulty with the sun will find it is not needed at Epcot, where all the waits are inside. Even at the other parks, most of the lines are well shaded. GACs for sun exposure are also not used at night - no sun.
As someone posted, exactly what happens with a GAC depends on things like what the GAC says, what is available at that attraction and what is happening at the time - so it is variable and can even be different at the same attraction on the same day, but at a later time.
So, they are not Fastpasses. They are not front of the line. They are accommodation for people with disabilities.