I'm surprised this is such a divisive debate, but then realised this is on chat, not the SEN area. So the depth of knowledge of the RAP system and Neurodivergent conditions is probably less well understood. I get that if you don't have experience then you may have obvious thoughts like "why are they at a theme park" but medical professionals like OT will answer that with reasoning.
I can't speak for ADHD/anxiety as I don't have experience of them.
Whilst there is so much I could say on this topic. A diagnosis is not an entitlement to anything. It's about needs alone, anyone who has done DLA and EHCPs will understand this. It's no different here, ASD/ADHD doesn't mean you need RAP, but there are plenty of people that do.
The purpose of RAP is not queue jumping, that is a paid service called fast track, which RAP holders can buy as well. The service can be abused in many ways including by those who can queue, but also gaming the system to get on more rides. Nimbus is more strict compared to Merlin who didn't request evidence at least when we had it.
The purpose of RAP is to provide a reasonable adjustment, not preferential treatment. If the park is busy and people only get 5 rides in, RAP users should also get the same 5 rides. There are flaws in RAP that Merlin could fix, but they haven't and people do abuse it.
The main issue I have in all this is the communication of it all. Merlin gave just 2 weeks notice before the park opened. Nimbus on the other hand, still haven't said anything, only posting up FAQs on the website. Nimbus pass lasts 3 years, they only keep medical evidence for 90 days, but have reassessed everyone, without asking for evidence to make a decision, then didn't tell anyone about the decision they made. Their FAQ implies a split between physical and neurological conditions. This is why everyone is saying hidden disabilities have been put into 1 category.
I think Merlin have made a massive mistake here. Merlin offloaded their assessments to Nimbus, who then have told them to provide a virtual queue as a reasonable adjustment, but Merlin refused.