At Disney you've got a wide variety of wheelchairs and scooters which are in various sizes so you can't as easily design a one size fits all loading system when the items loaded are going to vary. I think that's the reason they always pull out the actual ramps to that a wheeled device can be wheeled on without having to worry about wheels getting suck in the cracks between the train and the loading platform.
First thing to note - the monorail and the platform are not at the same level - there is a step up from the platform to get into the monorail.
As someone with much experience with an ECV and Disney monorails, there are a few issues with the Disney monorails and their ADA ramp system:
1 - the ramps are put into place manually by the operator, some can do it quickly, some are much slower
2 - the width of the ramp only gives 2-3 inches maybe on each side when an ECV is pulling into and backing out of the monorail car
3 - the angle of the ramp is somewhat steep, and if the ECV driver isn't used to the ramp, especially when backing out, it can slow things up
My suggested solutions:
1 - make the ramps wider
2 - make the ramp longer? so the angle isn't quite so steep, ideally the monorail would be the same level as the platform, so if a ramp was used, it would be level and just be a means of covering the gap
3 - wishlist, blue sky item! Have a few cars on each monorail that have a turntable in it so that the ECV or wheelchair doesn't need to back out, the turntable would turn it around!!! HA!