While we always take late seating, situations such as described by the OP happen all the time in restaurants. It's not the kids, it's the parents who want to enjoy adult time and forget they are parents. I was having brunch at a pancake house once - the table next to us had a fairly large family group. On small boy kept wailing "mommy, mommy, mommy" constantly - mommy was much too busy chatting with everyone else to care. It was getting way annoying. I finally turned around and snarled "excuse me, MOMMY!" She seemed shocked. I asked "why is it that everyone in this restaurant can hear your child but YOU?"
Another time, on a cruise, I was at the pool - the woman next to me had two boys, maybe 7-9 years of age. After downing several "virgin" frozen drinks, they were still bored and complained that there were too many adults in the hot tub for them to play. "Well, then" she advised "just go jump in and splash around a alot and they'll move." I gave her my best school teacher glare, but was relaxing and didn't feel like getting into it. She seemed quite proud that they were now out of her hair.
It's really all about the parents. My sister has five grandchildren under the age of 7 - you can take them anywhere. Last Christmas, they were put at a "kids' table" just off the dining room. They ate without a peep and then politely asked to leave the table. They were told yes, but they had to sit quietly in the family room and read (or look at picture books) until everyone else had finished eating. Granted, they are being raised by three teachers and an ex-Marine, but . . . . My grandchildren, alas, not so much.