Depends on the bar, most places that can get the bartender fired.
As to kids, I worked this one bar that was decidedly a bar. A chain called Hueys in the Memphis area. Well, lots liked to bring their kids in after a softball game or whatnot. The kids could be amused by trying to shoot frill pcks with a straw into the ceiling (and at each other). The parents would drink beer and sneak to the bar for a shot. No big deal, the regulars would tolerate it as they knew the little ones would move on.
However, enter the Dizzy Dean World series which was like 2 miles from the Hueys I worked at. The place would be packed with several teams at a pop with all their families. It drove the regulars out for that week and more. Many would not come back for ages. So we were told to try and rein in the kids. When the manager left, the bartender (me) was in charge. So we get two teams in one night and the kids are running all over the place looking for the "playground" no doubt. There is a crowd of about 12 at the front door alone making it almost impossible for new people to come in. I approach the table those kids are from and ask who is in charge of the group. Everyone points to this one lady so I approach her and say, "Hi, we are glad you decided to come in tonight. However, your children are running around and disturbing the other customers (we never said guests and it was frowned on actually). They are also blocking the door and making it hard for new customers to come in. I would appreciate it if you could have them return to their seats." She stammered out something to the effect that she would see what she could do.
About 5 minutes later (kids still treating the place like a playground) the waitress comes up to me and said that the woman said, "You tell that bartender that I can't control these kids and if he can, I will suck his big toe."
Now besides the bizarreness of admitting the parents have no control over the kids, she brings toe sucking into it? At least it wasn't at the end of my shift...
So I approach the group of kids at the front door and say, "You kids can't be up here. You need to return to your seats and wait on your meal." Oddly, they all did. I waited till they were all at the table and walked by winking at the woman. I wanted to pull up a chair, take off my sock and shoe and say, "Your turn."