My son has the type of autism that is not a hidden disability

My son was running away from me in the supermarket yet again. I had held him tight as we went through the checkout but let go of him for a second or two to pick up my bags. That was all it took. As I chased after him towards the automatic front doors and into a very busy car park I noticed a stranger was gently holding his shoulder.

“Is he yours?” she asked as she saw the sweat appear on my forehead.

“Yes”, I puffed as I once again held his wrists.

“He has autism and he is heading right for the car park lift. Thanks for your support.”
“I knew right away he had autism. You can tell.”
If I was given just a small amount of money each time someone told me something similar I would be rich.
My son has the type of autism that is NOT a hidden disability.

So what makes his difficulties and diagnosis so obvious?
Is it the fact he flaps and stims CONSTANTLY? I really means constantly! He can not sit or stand still. He shakes things, chews things, flaps things, flicks things, squeezes things and licks things all the time. It is impossible to NOT notice it. His body movements are not hidden.
Is it the fact he can not talk? That may seem like something you would think would not be noticeable but to hear the noises he DOES make it is pretty clear to most people that these are not noises you hear everyday. His noises are not hidden.
Is it the fact he screams? He can scream longer than a fire alarm and more high pitched that a whistle. He screams randomly and inappropriately whenever he feels like it. There is nothing hidden about that in any way.
What about the fact he is still wearing nappies? As much as I try not to show this he thinks nothing of pulling up his top to chew or pulling at his trousers making it obvious. He has no social awareness and no understanding. Yes he could be incontinent for any number of reasons but combined with his noises and movements it adds to the number of reasons why people realise right away upon meeting him that he has autism.
He runs, he flaps, he obviously has learning difficulties, and he behaves quite differently to other children his age. He is sometimes in a wheelchair for his own safety and if I have not got the energy to run a marathon while doing my shopping then I often use a disabled trolley for convenience.
He would rather spend hours at hand dryers in the bathroom than anywhere else in a store, unless they have a lift. He is entertained for hours just watching lift doors open and close and open and close over and over again.
He is unmissable. He is loud. His tongue is more out of his mouth than it is in. He is handsome, cheeky and adorable. I don’t hide him and I don’t hide his autism. He doesn’t hide his diagnosis either. In fact he flaunts it.

People see him and people see his autism. 
Sometimes they don’t react very well to that. Other times, like the beautiful stranger today, they see a child with obvious difficulties and look out for him.
They comment, they look, and they react because my child has the type of autism that is NOT a hidden disability.
For many who are not as severe as my son I understand why autism can be a hidden disability. But it isn’t true that it is a hidden disability for everyone.