Actually Walmart does not allow it, but most stores don’t care. My local one had a guy unalive himself in his car surrounded by other multi day parked cars. It took them 3 days to see all the others cars leave and he was inside. So now they enforce it. Understandably so.
As a fellow autist my experience was most people could “sniff” it out even though my parents couldn’t. Women in general were kinder to me out of almost pitty, while men left me alone and just othered me more. Both took advantage of me but I enjoyed the pitty more as a child.