You said that parents should try to soothe their children to keep them from bothering other travelers. No one here would disagree with that. NO ONE. But trying doesn't always make someone successful.

I agree that parents should recognize that there are others traveling. Perhaps you should recognize that others were traveling too - including those parents with the child.

Again, I expect them to do their best to quiet the child. But when it's me traveling and another person's child is upset, mostly I'm just glad it's not me with my child. It's silly to think that people with children should simply never travel and/or never travel with the child.