It’s the parents.
I dont know any toddlers and children that themselves put food on the table.
My kids love bread, tortillas, potatoes, pasta, beans, rice, and oats Why wouldn’t they? There is no need for kids to love kale, brussel sprouts, or salads. They will get plenty of everything just eating starchy vegetables, tubers, legumes and grains, which is a natural preference for higher calorie density foods kids need to grow.
Bread and tortillas at 1200 calories per pound would be roughly equivalent to the energy density of meat. Peanut butter or other nut butter ar 2600 calories per pound would be roughtly equivalent to other very high energy foods. There is no need for parents to worry about kids wasting away. (Parents might themselves want to limit these higher energy foods for themselves.)
When parents change, kids will change. Tantrums and such will be overcome in short order. It will not kill kids to miss a meal or two if necessary. Kids won’t starve themselves for long.
Have a bowl of fresh fruit always available on the table. Keep some cooked oven fries, mashed potatoes, beans, bread, and other staples pre cooked and ready in the refrigerator for fast foods. Have a routine. Make the food taste great.
Getting kids involved in the kitchen, garden and shopping also works. For example, in my house, Thursday and Saturday are bread-pizza days, and they receive their own dough to shape and bake. They chose and cut the fruit for their breakfast cereal, and help making fruit salads. I take the kids shopping and we select the produce together.
Finally, a podcast I enjoy is pediatrician Dr Yami Cazorla-Lancaster (Veggie Doctor Radio)
https://veggiedoctor.libsyn.comAlso PCRM
https://www.pcrm.org/good-nutrition/nutrition-for-kidsand Plantrician Project
https://plantricianproject.org/quickstartguide (A guide specific to children)
https://resources.plantricianproject.org/tools-and-resources