I'm sorry for rudeness you received, we have occasionally run into clueless CMs. On common place is Small World, where one CM might tell people to go direcctly to the wheelchair pull off point, while another CM tells them that they can't do that and need to go in the regual line until it reaches that point.
We (and other people) have also had problems at times with Splash Mountain, even with a GAC for a person with a wheelchair. The CM insisted we had to 'stay in the regular line'. We tried to explain we could not because the regular line had come to steps. There is always a supervisor who can help in those situations.
But one of the things people need to keep in mind is that things do change from time to time. We saw several people going in the exit at the ride at Mexico because that's what they have done on past trips. They were confused when the CM stopped them at their 'usual' boarding area because they were going in what they thought was the 'wheelchair line'. But the line was renovated and you now go thru the same entrance as everyone else.
Sometimes the guest with a wheelchair or
ECV is pulled out of the regular line (for reasons not obvious to the guest). The guest might think that means there is a 'wheelchair line' for that ride on future visits and then be surprised not to be put in that 'wheelchair line' on subsequent visits.
Most people using wheelchairs or
ECVs don't have need for anything other than a wheelchair accessible line, so they don't need a GAC. And, since most lines are totally wheelchair accessible and the CM can see they have a wheelchair, they would be in the accessible line, if it's not the 'usual' boarding area. That is likely what happened when the CM did not look for your DD's GAC. You were doing what everyone using a wheelchair does in that line, so didn't need a GAC to do it.
Over the years, lines have gradually been changed from having a wheelchair entrance to what is called "Mainstream Lines" which are accessible and everyone waits in the same line. Some of them have a wheelchair boarding area that you are routed to not far from the regular boarding area, but you don't need a GAC to do that. If you need more accomodation than just having the wheelchair in line, then you do need a GAC for the Mainstream Attractions.
Here is a list of Mainstream Attractions from the WDW Guidebook for Guests with Disabilities (there is a link to the Guidebook in the disABILITIES FAQs thread):
Magic Kingdom® Park
Ariel's Grotto
Astro Orbiter
Buzz Lightyear's Space Ranger Spin
Donald's Boat
Judge's Tent
Mickey's Country House
Mickey's PhilharMagic
Minnie's Country House
Monsters, Inc. Laugh Floor
Pirates of the Caribbean
Space Mountain®
Splash Mountain®
Stitch's Great Escape!™
"The Enchanted Tiki Room Under New Management"
The Hall of Presidents
The Magic Carpets of Aladdin
The Many Adventures of Winnie the Pooh
Tomorrowland® Indy Speedway
Toontown Hall of Fame
Walt Disney's Carousel of Progress (seasonal)
Epcot®
FUTURE WORLD
Imagination!: All Attractions
Innoventions East
Innoventions West
Mission: SPACE
Test Track
The Seas with Nemo & Friends: All Attractions
The Land: All Attractions
Universe of Energy: "Ellen's Energy Adventure"
Wonders of Life: All Attractions (seasonal)
WORLD SHOWCASE
China: "Reflections of China"
France: "Impressions de France"
FriendShip Boats
Norway: Maelstrom
The American Adventure: "The American Adventure"
Disney-MGM Studios
Disney-MGM Studios Backlot Tour
Fantasmic!
Lights, Motors, Action!™ Extreme Stunt Show
Muppet*Vision 3D
Playhouse Disney - Live On Stage!
Rock 'n' Roller Coaster® Starring Aerosmith
Sounds Dangerous - Starring Drew Carey
Star Tours
The Great Movie Ride
The Magic of Disney Animation
"The Twilight Zone Tower of Terror™"
Voyage of the Little Mermaid
Walt Disney: One Man's Dream
Disney's Animal Kingdom® Theme Park
Caravan Stage: "Flights of Wonder"
DINOSAUR
Expedition Everest™
Finding Nemo - The Musical
Grandmother Willow's Grove: "Pocahontas and Her forest friends"
It's Tough To Be A Bug
Kali River Rapids
Kilimanjaro Safaris
Lion King Theater: "Festival of the Lion King"
Maharajah Jungle Trek
Primeval Whirl
The Boneyard
TriceraTop Spin