It's rare that I find an adult even capable of reaching the decible level of a screeching child. In the defense of the children, however, I'd also like to say they're only doing what their parents condone--and in some cases, the tots are too young to understand how to behave in a restaurant or a movie, especially at a movie, because that's a couple of hours minimum, a long time to have to sit quietly for a wee one. This is where the concept of "babysitter" should be considered.
I go to the local McDonalds for coffee. There is a bunch of blue haired "ROMEO"s (retired old men eating out). Each and every one of 'em must be deaf as a board. None of them talk in a normal tone of voice. They spend their time drinking coffee and yelling at each other about the day's events. Just as bad as kids...
And this is apropos of what? Because there are bratty adults that means we should tolerate bratty children? All you've done is create a straw man argument to completely deflect from the real source of the evil. Over-entitled, bratty adults raising even more out of control and noxious "children", if you can call them that.
I have to agree with you on that. If establishments are going to ask children to behave with "indoor voices" then the same goes for obnoxious loud adults.