If you have to deal with a child who, unfortunately, lacks "normal" control mechanisms when in public places, then you refrain from visiting the same with said child. Problem solved. If you want to reply with something to the effect that taking this child out in public places is unavoidable, at times, I'd say you need to rethink your situation and consider having a sitter/child minder when you must venture out in public. No, I am not heartless. I simply am considering the rights of the many, to not be disturbed by a caterwauling individual, over the right of that individual to scream his/her head off, in public. (No such right exists, in any country that I know of.)
OK maybe we should just lock all those children away then out of sight out of mind would that suit you????...............you may not think you are heartless but you are heartless with no understanding........ people are obviously more tolerant and understanding where I live.