I have kids too. I'm not going to pretend that I have all the answers. But parents have lost the ability to properly impart etiquette to their kids, in many cases because they have none themselves. So kids' behaviour in public has gotten worse. Simultaneously, adults have become spoiled brats unwilling to tolerate even the slightest discomfort, which is why you have people whining about having to listen to crying babies on flights. For fuck's sake babies are the literal future of our species.
Kids' etiquette needs to be improved.
Adults need to grow up.
I've travelled around the world, and it's only the so-called advanced Western countries that have this problem. For example, I was in Vietnam recently and kids' public behaviour was practically alien compared to kids back in Australia where I live. When kids did cry or make a ruckus, nobody even looked up. It was just understood that that is what it meant to live in a society that had kids.