It really strange how american kids are so I'll behaved compared to most places here in Europe. Definitely systemic factors at play.

It is not. You are giving a wider scope to something very trivial, such as feeling upset by sudden and very high noises, and the annoyance of little kids running around unsupervised. There is no higher meaning here, just the need for education.

That's where these rules come from. The staff has to make a choice: tolerate the unpleasant behavior, or risk ratcheting it up to even worse behavior by intervening. It was bad for business, so they made rules. They knew it would cost something; they believed that the benefit was worth the cost.

I do believe that it's incumbent on adults without children to tolerate children to a considerable degree -- more than seems fair to them. But I've also found that a lot of parents consider "I'm raising the next generation and therefore justified in demanding infinite tolerance" to be valid, and that's just not right. When we can't negotiate a middle ground, extremes get set.

That, and also the glomy future our kids would have had. The biggest culprits of climate change and pollution aren't giving signs of stopping anytime soon (even more with the recent demagogic resurgence), and while we'll be dead in a few more decades, the younger generations will live in harder times than we did. Not having kids is also an abstentionist stament, because people who want more kids overlap significantly with people who don't care about the world they'll be leaving to those kids.