It’s a good rule of thumb but it’s not totally that simple though, I know lots of kids who cannot manage ADL but can manage IADL (I work in an unusual school that is exclusively for kids with a primary diagnosis of autism and who are also roughly average or above academically. We take all and any levels of need in terms of their autism but they must be (roughly) age appropriate - meaning at least within a year or two - academically. I am personally (very) low needs in society although I’m also pretty obviously autistic by people “in the know” due to my communication and sensory issues, and I have a medium ASL needs kid who does quite well with IADL type things.)

At my school we have lots of kids who can manage their school work, do their home work themselves, can gather their own equipment for a lesson, self start a task by following a complex set of multi-step verbal or written instructions and complete a high level living skills or academic tasks eg answer abstract questions about history, or follow instructions to learn to do their own clothes washing or make a dinner, but yet they cannot verbally talk or toilet themselves or select weather appropriate clothing to wear after a change in weather. Those ADL tasks are not as rule bound as a lot of more “advanced” life skills. They require a level of change, flexibility and innovation that many IADL tasks don’t. It was dry when I dressed but now it’s raining. I am in lessons but now I need a poo. I cannot choose my own food or feed myself in a “socially acceptable” manner due to my sensory issues, but I can write coherent sentences about the preindustrial age diet. I can wash my own clothes because there are rules for how and when to do it, but I cannot then wear those clothes because I cannot handle the sensation of the label and will not independently consider cutting them out so instead will just scream and take all my clothes off.

ADL can be more messy and change more often and more unpredictably I guess. Going to a shop or to work where there is a set uniform, route, tasks, set interactions etc is more manageable than bodies and all their messy ways. A shop is always basically the same process if you wear a coat or not, but knowing when to wear the coat in the first place depends on a lot of factors that aren’t always black and white and that small ADL thing can cause the total melt/shutdown instead of the actual more complex shopping IADL task.

I do think there is a big difference in experience between someone who is non verbal and not obviously intaking communication either, and someone who is “functioning” socially with, say, a late diagnosis, so I’m very in support of the idea of spicy autism and including those voices in the discussion. Personally I’m here to learn more about what their lived experience might be like so I can better help my kids at school who are really spicy.

I actually think spicy is the best word I’ve ever heard as it doesn’t try to categorise autistic folk by NT ideas of what a person should or shouldn’t be able do to live a life they value. It instead bases it more on how “acceptable” you are to mainstream society. It says so much in its vagueness. I score high on an ADOS but the issues mostly affect me on the inside, in lived experience spicy terms I’m a korma - everyone can handle me, my issues are largely seen as my own personal problems to deal with. My kid scored full marks on the ADOS and she’s in mainstream education with some extra support, she’s more like like a wasabi pea. Some people absolutely love her, most will tolerate her, some people just cannot deal at all. She will probably be able to function independently as an adult at some point (after a bit of trial and error), but will probably struggle with finding/keeping friends and her mental health for the rest of her life. She will always be noticeably different from the norm, she will always need to ask for accommodations but they are of a sort people are generally willing to make. I have kids at school who are more like a death pepper. They actually are fully aware and very bright, they are really able to do most things asked of them but their inability to verbally talk or their extreme inflexibility when things change or unmanageable sensory issues render them utterly unpalatable to 99% of the population and unlikely to live independently or hold down a job. People are uncomfortable around them and jobs will be generally unwilling to accommodate their needs as they are so far outside the norm, although they are more than able to do the actual work if their needs were accounted for.

Official functioning labels, however you categorise them or whatever you call them, are (IMO) really about how acceptable you are to mainstream people, couched in rules and guidelines that make giving that label feel acceptable to the mainstream society that imposes that value judgement. In reality people are much more complex and messy than these categories, which are at best of a vague rule of thumb. People are more complex than something that can be pinned down to a few pages in a diagnostic manual, but that is the best we have for now.