Hey, i'm autistic and almost 30, and have been dealing with this sort of conversation my entire life but starting before the pandemic I went about trying to understand why it goes like that when I'm not coming at the conversation with an argument. What I've found is, well, think of it like the conversation is a road, right, and the neurotypical expects that road to go a certain way with certain turns and destination. If the conversation doesn't go like that, then the neurotypical assumes there's a disagreement and if that disagreement cannot be resolved then there must be a "problem", which they do not handle very well. For all they call us rigid, they very much are too, lol.

"Why?" ,such as in your example, is like throwing a stop sign in where it makes no sense to have a stop sign. Typically, neurotypical conversations follow similar paths and patterns, so if you know what they want going in you can respond with sort of tangentially related things which they can work with, with the ultimate conclusion being that you're not interested in this case.
so like,
"You need to eat something"
"I had x,y,z for lunch"
"Lunch was a while ago"
"I know"
"would you like something to eat?"
"no thanks but i'll let you know if i change my mind"

and then you really don't have to get back to them if you don't want to. it takes a bit of getting used to, but thankfully i've been able to find a method that works with my own patterns that still gets my point across. it used to be like hitting that stop sign that made no sense to be there when a neurotypical would ask me something, but the way i reply now is able to maintain my personal flow so the questions and interruptions don't actually stress me out anymore. Ironically, when it comes to social stuff because people inherently want to get along, there's a lot that will fly that you might not think would right now. I always hated being told "fake it till you make it", but its honestly the best advice i've ever received when it comes to stuff like this. Soon you get to a point where you realize NOBODY knows what the social rules are so we're all just faking it, but by then you realize its kinda fun so its not so bad after all.

Hope this helps!

It does help. I appreciate this as you're someone who has had time to experience this and put it into words. Thank you so much. The visual is really helpful to me. On an autism road, there's a pretty short distance between the stop signs which might throw a neurotypical offguard--it's a completely straight road with no turns. Neurotypicals don't expect us to have a specific response, but there's a different pattern woven in response. I was like thirteen-ish about 5 years ago and that's when it dawned on me that if people are asking me about how I'm doing, they probably don't want to be bombarded with facts about ants, nuclear bombs, and pokemon lol. Thank you so much for this. Lovely gallery, btw. I can see some genuine talent in both your traditional art and photography.