It's just marketing, Monique. They say you "should" wear one, and they would love it if you would. They probably have one for hangnails too. Autism is a different story and I do think it's a good idea for your son, especially if he goes to school or out with friends.
I keep a card in my wallet with a list of my meds and a description of where I am with the MS so that if something happened, it would be found. But, in an emergency, standard stabilization would be no different for me as any other injured party.
My cell phone has a phonebook entry of I.C.E. (in case of emergency) with my brother's cell number. They would call him if I were incapacitated.
I have a "vial of life" in my refrigerator that lists my conditions and corresponding meds, you can get one of those at any drug store. It's basically just a regular Rx bottle with a label and medical rescue personnel are trained to look in the fridge to find it.
Beyond that, my life just goes on. You're a smart girl, you'll know what to do for yourself and your kids.