I see a lot of objectionable behavior out in public. A lot of it is from children. But most of it is not. If I'm thinking through my 10 worst flight experiences, or subway experiences, or coffee shop experiences, none of them involve children. Children are mostly a mild annoyance (and I say this as someone who mostly doesn't like other people's kids), but mostly harmless.
So the reaction of singling out the children for immediate correction, through physical force and violence, seems to be selectively targeted, and makes me suspect it's just people who just don't like children. Unless these same people say that a person holding up the line, playing music too loud on the subway, getting too close in your personal space, throwing trash on the ground, catcalling women, using slurs in public, etc., all deserve to be beaten, too.
And for people in the thread who are saying stuff like "oh yeah you shouldn't beat your kids, but you should keep those children out of public places," it also calls to mind the way some people talk about the homeless or the disabled, like they're ruining your good time by simply existing within your vicinity.
We're all just trying to coexist. Being in public, in a place open and accessible to everyone else, is inherently going to involve compromise, where we're not able to exclude others (the deal that comes with them not being able to exclude you). You can't let other people aggravate you enough to, like, post a TikTok about it (which I also consider to be objectionable behavior).