I am totally fine with well-behaved young kids out for a nice meal with their parents, at Red Lobster or Olive Garden or a comparable place. That said, my folks didn't take me to a really nice, grown-up spot until I was about 10 years old and had some civilization put on me! I knew how to eat with proper utensils, and could remember what they said about which fork and where to put your napkin and so on. These occasions were usually because my old-school, formal, traditional grandparents were in town for a visit and my grandmother would have died of shame if her grandkid was a mannerless, ignorant lout.
That said, I believe that young kids shouldn't be taken to non-kid-friendly places not because they can't handle it, but because it's such a boring experience for them. It's setting the kid up to fail. Leave them at home and have a nice adult evening instead!
Oh, and I firmly believe that it's totally possible for very young kids to be quiet, stay in their seats, and not shout, scream, or have a kicking, screaming, arching-the-back fit in a restaurant. My bro and sis in law have two kids, both under 5, one with significant issues (including sensory issues) and my mom-in-law likes to take all her kids and her grandkids out for dinner, a lot, about every 8-10 weeks. So I get to see my nephews (who will be 2 and 5 this fall) behave wonderfully in restaurants. Every time. Do we go to a fabulous steakhouse with a dress code and Lennox china? No. We often go to Olive Garden or somewhere like that. But even the staff compliment my in-laws on how they've put manners on their kids. Usually my in-laws bring crayons and a notebook for the kids to draw on while we wait for the food, or a quiet book, or something.
I am very very NOT OK with shrieking, bored, uncontrollable brats that run in between the server's legs, throw tantrums when they don't get their way, or shriek piercingly for 45 minutes because they are overtired and need to go home to bed. If my sis and bro in-law can make their disabled 3 year old behave in public, then surely it's possible for others to do so as well.
Though in all fairness, instead of trying to 'fix' the situation or telling off the offending parents, however politely, I usually just get up and leave. There are other places to eat. If I'm in a sit-down place and waiting for my bill, I'll leave the table and go to the hostess stand and tell them why I'm leaving, and present my payment to the hostess. I have never once been given any difficulty about it, and usually get an apology from the restaurant staff.
I really vehemently dislike feral children who not only haven't been taught how to behave, but don't care to be polite because they're disrespectful brats. If I see that going on, I will immediately turn and walk out. I might not be able to control how (or if) people raise their children, but I can darn well make sure that I don't have to endure it when I'm supposed to be having a good time.
Whitewater