I just feel like there are a ton of parents who seem to feel that kids should be able to run free, or that its not their problem to watch their kid.

In a literal sense, sure. A ton of people is actually not very many people, even if they're all underweight.

But I see people make this claim over and over again, and I gotta say - it never matches my perception, which is that most kids are about as reasonably polite as most adults.

in fact scream at everyone else that its their fault that precious Susie refused to listen and got scratched

I've never seen this

Or precious Liam tripped the waiter because you all had him running around in the restaurant and refused to get him to sit down, but hey, its the waiters fault somehow

or this

precious Jenny has just turned over a pile of clothing in the store and well isn't it your job to clean it up? How dare you be pissed off at the extra work for shit pay

or this!

And like why would you not have headphones for folks who are watching media on a plane bus or any enclosed area? Of course loud as hell media on in already uncomfortable and enclosed space is bloody annoying!

I *have* seen this. It is just as likely to be adults only who are playing their music and videos without headphones - and the sneering resentment I got the one time I told a couple to turn it down because my two niblings had massive crippling migraines and we just had half an hour more before we were home and they could go to bed. Like, wow.