When a child is in distress, he literally has no way out other than to scream and cry about it. You have to physically build the pathways in your kid's brain to give them that path to cope and return to equilibrium. And that means sitting with your child through his emotions and letting him copy your mind while you calm down together. It starts at home, and if you're in public during the meltdown, you're too late.
I may not have kids, but watching relatives deal with their kids by constantly yelling at them gave me a strong cautionary tale of what not to do. I'm of the belief that kids mirror the emotional life of their parents. If the kid is unable to manage his emotions, there's a good chance the parents are unable as well.
