Every omnimover should have a wheelchair car similar to Mermaid and Nemo. There’s no excuse for rides like Buzz, Haunted Mansion, Spaceship Earth and Figment to not have a roll in option. I’d imagine Peter Pan’s Flight could also manage it would just be tricky given the aerial track.
Honestly I’m shocked that Runaway Railway didn’t have a roll in cart upon opening, wheelcahirs have their own loading area why not a wheelchair specific car? I imagine Ratatouille is going to be a similar situation, but it truly cant be that hard for a roll in car to exist if rides like Toy Story Mania, Jungle Cruise, and Kilimanjaro Safaris so can all these others.
Nemo is able to load without stopping the ride vehicle it sees cast members handling the wheelchair as they get the wheelchair onto a car. The car itself has a ramp that swings out onto the moving walkway allowing for a wheelchair to glide right in.
Not in the same vein but in Star Tours (Terminal B) they are able to detach the armrest on the left most chair allowing for guest to more easily slide into that seat if possible.