You have zero knowledge of Autistic compulsions and obsessions. He has no inhibitions, awareness of danger or reaction to pain. He is abnormally strong, he cannot walk past shop windows without entering the shop. And has to be dragged away in full mental breakdown. He can't pass cars without touching them and likes to collect car badges. Strange areas or sites, sounds over stimulate him. A trip to the shop involves a half hour conversation on what he HAS to do in there and a shopping list he must follow. Actually I'm so angry at your response, I'm going to stop there. You're clueless and patronising.
I have a good friend that is Autistic actually, my mum was also a child minder for years when I was growing up. She looked after an autistic child and one kid that had severe ADHD behavioural problems. They were all treated the same and she walked us everywhere. To and from School and large supermarkets for shopping. Disipline and structure was kept, despite the sometimes very embarrasing way the kid with ADHD would act, if he wanted something or just didn't feel like going to the shops. Screaming/kicking/punching and running around the store like a maniac. All were handled very well with big improvements over time.
Parking 10 metres closer to the store entrance doesn't solve any of the issues your son has, end of.