You don’t have to look past the first page results on google search as to why this type of food is BAD for your kids but restaurants will not change their offerings until people demand it by dollars spent.
I’m really not sure where the ‘kids Menu’ started but as a parent I can tell you that the regular menu (provided it’s not a hot dog stand) is always a better option for your kids.
You can share adult entrees with your kids (most restaurants serve enough food in a single adult entree for at least two people) or you can split a main entree for 2 kids and get them to eat a few vegetables with it if they come as a possible side dish. I find that some kids menus are getting better but there is a long way to go improving the food choices.
One of the tools we have available to us as parents is that kids want to be super hero strong and I always use that reinforcement to explain to my daughters that being strong and healthy is like a superpower and that they will always perform their best if they eat well and get exercise. Using leverage of healthy or strong characters seems to have a real impact on them and when they use logic to make their own decisions about food it seems to really empower them. The old version of this is the Popeye character and his spinach but this is now of course, out of date.
My daughters have an expectation of having to eat some vegetables before every meal. From the very beginning of their lives after breastfeeding (thanks to my wife!) they have been expected to do this and veggies is something they enjoy a lot nowadays! I teach my kids that health is power and they truly get excited by it!
Children's Health in the United States is becoming an important topic, the statistics on lifespan and overall health for this youngest generation are abysmal at best.
We need to do everything we can to help today's kids make the right choices with their food so that they can grow healthy, happy, live longer and actualize their lives to the fullest capacity!