I was speaking in generalities based on my overall experiences. Yes, I agree it is not ok to let a child run out of control just because it is a family restaurant, but nonetheless you will see lots of families with out-of-control kids in such places.
Also, responsible parenting is not something limited to the "well-to-do" and is in fact often lacking in that social group. However, I have noticed that in more upscale restaurants the socially conscious "well-to-do" types the dine there are typically motivated by a desire not to be embarrassed by their offspring so they will keep them under control. Again -- this is a generality. My point was that people who don't want to be bothered by unruly children can make choices that make it less likely that they will encounter them.
The fact that it's a family restaurant doesn't make it okay to let little Johnny run amok and annoy the other patrons.
"...the well-to-do parents won't tolerate the little darlings embarrassing them in public."
My parents weren't well-to-do, and they would never have tolerated bad or rambunctious behavior us in public.
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My double cousin Rhonda kept her aging parents in a garage bedroom with bath. My mother's sister married to my dad's brother--Aunt 'O'--had Alzheimer's.
Sometimes they desperately needed to eat out. They'd go to a nice place with a big booth in a U shape and put 77 year old Aunty in the middle.
Otherwise, Aunty would gobble her food quickly and then roam around to the other tables sampling their food or trying to.
One time, with Aunty seated in the middle of the U, aunty started the children's favorite of slinking down to the floor to crawl out and go roaming around the other tables to sample their food and ask them if she could go home with them because her daughter treated her so mean (total fabrication).
Finally, in exasperation, Rhonda said to her mother:
"Mother, if you don't sit still and be quiet until we are finished eating, I'm going to cast the devil out of you right here in front of God and everyone!"
Aunty replied: "You wouldn't! Would you?"
Rhonda: "I certainly would!"
Aunty quieted down, amazingly.