I've never really encountered this to be an issue. While there a few kids that are hopeless because their parents have no ability (or the sense to fix it) to control them, most kids at restaurants usually don't make much noise or cause a scene. Why? It's because they have something to do. Most kids are at their worst moments when they're bored out of their minds. Most of these times, it's with mom while she's looking for crap that she never needed in the first place. I know because that's exactly how I remember it when I was young.
Do they bother you while you eat food?