It depends what type of restaurants you are talking about...we ate at Ohanas, Le Cellier, California Grill, Boma, Jikos, Biergarten, Tusker House (breakfast), CRT (breakfast).
At Boma, Biergarten, and Tusker House...they can eat off of the buffet...anywhere. My children ate lots of yummy, healthy food. At Le Cellier, California Grill, and Jikos, the kids had options such a salmon, pork, grilled chicken, steak, etc.
At Ohanas, everything is family style. There is no menu. DD6 just opted to eat from the adults section. DS4, who had a double ear infection at the time, opted to eat mac and cheese (that's his feel good food) which the waiter brought specifically for him.
Even at Flame Tree Barbecue, our only CS meal, DD4 got a grilled chicken breast.
So, there were plenty of helathy options and we did not have to look for them...they were all on the menus.