And it can be done with out beating the shit out of them.
Indeed. For example, our youngest recently forfeited her dessert because she didn't eat any of her dinner. Having to watch her older sister eat a bowl of ice cream while she got none sent her over the cliff into a serious melt-down. But it had to be done.
Having raised 4 of my own, and additional 2 for quite a few years...I feel your pain.
I think at some point all of my boys have had to be escorted out to the car to wait while the family enjoyed a nice meal in a restaurant.
There was much wailing and gnashing of teeth. And not one of the tables we passed with said son screaming and thrashing gave us dirty looks, any of those times, lol. In fact, we all but got a standing ovation.
I have also left full shopping carts standing in the middle of stores when a child has gotten out of hand (and I was the sole adult in our party).
It's just one of those things we have to do...kids don't learn how to act in public if you never take them places. But when you do, be prepared to remove them from the premises if their behavior is inappropriate, or they never learn what behavior is inappropriate.