Respectfully, I'm sad for children whose parents think society is going to look out for them. Every kid deserves a couple of people who take personal responsibility for their behavior and well-being.
I have a pretty high tolerance for kids being bouncy and boisterous, but it's always nice to see parents giving the sort of information that helps them become considerate:("Look, that woman's trying to read. She wants it quiet!" -or- "That lamp could break - can you find a safer place to bounce your ball?")
Another big issue that isn't always mentioned is diet. A kid who eats a "normal" amount of sugar, corn syrup, and zero-nutrient high-carb products will understandably be going berserk on the outside because they're on a blood sugar roller coaster on the inside.
As an alternative perspective, I think that in France "kids are society's problem" doesn't mean building special places where they can run rampant, but training them to appreciate the culture and society they're inheriting. French kindergarteners spend 90 minutes sitting down to a white-table-cloth four course meal each day during school. This is done because it's considered essential for them to learn the table manners and appreciation of the cuisine that will allow them a lifetime of enjoyable, civilized dining.
(I think the creation of lots of "good", dignified jobs in the kindergarten-chef field is a wonderful side benefit, as opposed to cafeteria workers in the US who can hardly feel fulfilled while dumping bags of frozen nuggets onto trays.)
