why do children shout all the time?

They can be taught to quiet down. Unfortunately, many parents have abdicated their parental "power" to "instruct" their children... used to be called DISCIPLINING their children. One reason why is they fear public ridicule and/or "authoritative" retribution if they discipline their children.

We were not screaming "me-me's" as children because it simply was not tolerated by our parents. I recently confirmed this with my mother because I was curious about just the same thing. "Mom, were we screamers as kids? Cuz I don't recall screaming and crying all the time." ... she confirmed my remembrance... "No, we didn't allow it."

I work at a pizza place, and I hate the screaming kids who come in. They make me want to strangle them to shut them up. I usually say that I do NOT believe in the theory of the "Natural Child," where a child is allowed to "express" itself at any decibel level it so chooses.

In the "old" days, disciplining children was generally referred to as CIVILIZING them. These days, such civility has fallen out of favor. Mores the pity!

Have a polite day.

Because they are annoying little gits that like to let everyone know they're around and spoilt everyone else's day.

Because no one corrects them.