It’s never nice to make fun of someone for lacking ‘common sense’. It’s never nice to make fun of anyone, full stop.
In the example mentioned, the restaurant’s wording was unclear. But I would not have assumed that a child counted as one of the ‘party of 5’, because restaurants are money-making businesses and will have based their business model on 5 people drinking alcohol and/or getting the fancier menu items than usual at a birthday celebration, and that would cover the cost of the 5th plate.
If kids counted, you could theoretically take 4 toddlers with you who ate £5 meals from the kids menu and drank water and you’d get your dinner for free, and the restaurant would be out of pocket and have a god awful mess to clean up afterwards.
I wouldn’t have consciously thought all of that through in my mind, it would just sort of be there as an understanding based on having lived in the world a while and formed a mental model of how things generally work.
So I would have checked with the restaurant first.
I also don’t believe we can really change the entire world to suit the way everyone’s individual minds work - because outside of the average range there is just so much extreme variation. As everyone likes to say, if you’ve met one autistic person, you’ve met one autistic person.
And once you’re outside of that bell curve, very clear language helps to some extent, but you also need a kind of interpreter who knows the exact, particular things you struggle with.
As someone in a very neurodiverse family, it is way more than a full time job for me to do all the everyday thinking and connecting the dots and spelling things out for loved ones who struggle to understand a ton of little daily things, make inferences, understand how one bit of information relates to another, think of how to phrase a question, take basic care of themselves, or bring to mind what they ought to do in a particular circumstance.
Have a headache? ‘Common sense’ would suggest drinking some water, checking you’ve taken any regular medications, maybe taking an over the counter pain reliever. This is second nature to most people, but my relatives can’t make that connection and just go into a state of helpless panic because it was unexpected, and they don’t know what it means or what to do. These are people with PhDs, so no learning disabilities.
’Common sense’ means average sense, as someone else has pointed out. And I do think that having a very high IQ means your sense is uncommon in all sorts of ways, IYSWIM. As backed up by a lot of the literature about giftedness & twice exceptionality.
But when you are supporting numerous people who, for example, fundamentally reject the entire concept of looking for something because ‘how can I look for it if I don’t know where it is? That’s the most stupid thing I’ve ever heard!’ and follow you around debating the semantics of it all for hours while you find all their lost belongings and put them together for the day, you realise just how much human civilisation, collaboration and functioning relies on people being able to make connections and inferences, and find things out that they didn’t already know, and recall stored information that is relevant to the situation at hand.
I think a lot of ‘high functioning’ (esp with high IQ) ND people don’t have any idea how much support they need, and how much is actually being provided to them, all the time, by their loved ones.
And that it’s no simple, easy thing to identify what someone else doesn’t understand, and what exactly it is about it that they’re not understanding, and finding the bits that can be explained differently, and trying several ways to explain them differently, drawing diagrams, breaking it all down into sequential chunks, putting it in writing, making sure they can remember where the written instructions are stored, making sure you’re not asking direct questions / ONLY asking direct yes or no questions / not attempting to speak to them when they’re not expecting to be spoken to, etc.
Not everyone has common sense, and that’s just how the world is, and it means life can be pretty difficult for people who don’t have it and their loved ones - and it’s nobody’s fault, but for the most part nobody’s deliberately designed the world to exclude people who think differently out of sheer meanness.