I'm curious:
A reason often cited for RAP is the inability to cope with crowds, or crowded situations. This leads me on to two thoughts: firstly, I don't think I've ever been in a queueline that feels 'crowded' - it feels like a queue. You have people in front and behind of you, but unless behaviour is poor (which granted, sometimes it is), they shouldn't be actively jostling you, or acutely invading your personal space.
Secondly, and perhaps more pertinently, if the density of people within a queue is difficult to cope with, how do individuals cope with the density of people around the rest of the park? Or at supermarkets, or elsewhere in general life?
This is almost certainly coming from my naivety, and I would love to be educated on it, but crowds are a part of life, and if they are a genuine reason for creating reasonable adjustments within specifically theme park ride queues, I would have imagined that there would be many, many other walks of life in which case reasonable adjustments would also need to be made, probably as a priority over theme park queuelines.
To compare to a different access need: those who are not ambulant may struggle with many different queues, and as such need the reasonable adjustment of RAP. Look in other walks of life, and you have ramps, lifts, and other similar adjustments. I can't, with my lack of knowledge, understand what the parallel with an inability to cope with crowds would be.