I'm sorry but I find it shocking that a parent of a disabled child isn't familiar with fluctuating disabilities, or the spoon theory, or any of the other terms within disability rights that contradict this idea that disability is fixed and binary.
I suffered a massive stroke three years ago, it's very painful and dangerous for me to stand (since standing for long periods causes my blood pressure to drop due to POTS meaning I'm at risk of fainting), but I often have no choice but to grit my teeth and bare it since there's usually no option for adults with "invisible" disabilities to queue jump, and I have aphasia so have trouble articulating my needs verbally.
Some days I am in more physical pain than others, so I might be able to stand in a queue on a Monday but not on a Tuesday. It's not a case of "can or can't." It depends on the day.
If I decide to join a queue that looks small and like it will go fast, then the queue ends up taking longer than expected (because more people join, or there's a delay) I might have to leave the queue even after queueing for a few minutes because I can physically stand in a queue for only a short period of time. So again it's not as a simple as "well you joined the queue so obviously you're able to queue."
Or I might join a queue thinking that my pain is manageable that day, then realise after a few minutes that I overestimated my own capacity, and have to leave the queue.
A group pushing to the front would cause me to suffer an increase in physical pain and that increase might force me to abandon my place in the queue.
I agree that the world should accommodate disabled people better, that there should be systems were disabled people don't have to queue with everyone else, but no I personally as a mobility impaired person would not let a disabled child go in front of me as that would cause me physical pain and potentially force me to leave the queue myself.
Just baffled by the idea that only people with no issues queueing would get in a queue! People often have no choice! Obviously this thread is about a leisure activity but there are lots of things where you simply have no option to avoid queueing.