@Zeth0s @SRo it's because we fundamentally process language and interactions in a different way, our brains aren't wired for "small talk" or non-meaningful communication. Also the example earlier of context mattering where sometimes they might be asking with sincere interest and it can be catastrophic to fall back on a pattern like that.
And that's simply because we're either following an unnatural pattern that we've jury-rigged together from years of painful trial and error or we're thinking much harder about the words being said than you are.
We call this masking and it's a severe drain on our mental resources every single day and it's why it's claimed that we have a social problems (claimed because those problems completely disappear when interacting with fellow autistics, they're considered problems only because the majority expect us to do all the work of accommodating them and none of the work themselves).
Also, hi/hello are different from "what's up?" and "how're you?" despite being used the same by allistics (non-autistics). Hello is purely an acknowledgement, it doesn't even need to lead to a conversation, it's just basically saying "I know you are there and recognize you as a person".
Think of it like this: if you're in a dark house and hear a sound... do you say "what's up?" or "Hello?"
The others are formalities, evolved originally from real interest eventually into empty phrases. It has a lot to do with how allistics connect socially vs autistics.
We've recently begun to unravel the fact that allistics connect their social interactions and relationships to their identity while autistics connect values and actions. Because of that, I believe allistics put a lot more meaning into the form of an interaction than into the actual things accomplished in it.
"How're you?" was originally an expression genuinely asking someone about their day, a genuine expression of caring. However, since it became associated with caring it eventually became a formality, a shape of conversation in which "Hello" became seen as cold and uncaring... so everyone changed their patterns of speech for it and felt it much warmer... despite dropping what actually made it warm.
Us autistics however, we often struggle with casual lying because we care intrinsically about our actions, even the small perceived as meaningless ones. When we ask how someone is, we have the intent of asking that question.
Small talk is all about the "form" of the interaction. It's tied to allistic identity in that allistics typically seem to define themselves by the forms of their interactions. Autistics however couldn't care less about the form if nothing actually happens in it because we tie our identity to the actual things happening.
An allistic might consider themselves caring if their interactions take a caring tone and form... and they're often right (but not always, there's always that person everyone humors but can't stand). An autistic however might consider themselves caring based on the individual elements of the conversation, what was actually talked about and what happened during the conversation (ie. the person opened up, became less stressed, you got an update on what was going on, you were able to share inspiration, etc)