I guess I didn't even address the issue of the screaming toddler. Being a two year old is a very trying time even for your average toddler. They are just starting to get a handle on speech but unable to fully convey things the way they'll be able to once they're older. At the same time they are learning that they can have control of their environment and they want to control *everything*. This combination leads to frustrated kids (and parents) and often tantrums.
My friend Jessica has a two year old and he didn't want to leave the toy aisle. She finally had to carry him and he slapped, kicked, and screamed all the way through the store. She was thoroughly embarrassed. I told her it wasn't a big deal most people have either had a two year old or known one. I also noticed when she stopped reacting to his screaming he stopped screaming. (Some things do go away if you ignore them)
The wrong course of action is to "shut them up" by hitting them especially in the face. You know the article didn't say but I doubt the child stopped crying when he struck her.
In the case of the toddler I don't even think special needs has to be involved for a child to be unruly. Though on the flip side two was the age my son vanished inside of himself.
He's now thirteen. He dances, flaps, and makes a lot of noise where ever we go. People usually stare at us. He's about 5'7 and 175 right now and he's growing. He also likes to run backwards down the store aisle and slide on his butt down them. He's scolded for it but you know that impulse control part of your brain? He doesn't have that and he's so big I can't really stop him. I get looked at, glared at, and in some cases reported to management. He still goes pretty much everywhere. Neither my parents (who babysit him) nor I are willing to be shut ins 100% of the time when we have him. The funny thing is a lot of people know Joseph from the community and I also have people come up in the store to say "hello" He won't make eye contact but he'll give them a high five.
I've also had a bad run in with a guy at McDonalds that was mad because Joe wouldn't sit down and eat. The word autistic didn't mean anything to the guy. I ended up screaming at the guy to leave my kid alone in the middle of the restaurant. This guy was lucky though he never touched my son. Just kept telling me what a bad mother I was and trying to talk to Joe. I finally had to leave the restaurant because the guy wouldn't leave us alone.