Just one mother's observation in the why category. I see a fair number of adults giving their children special "kid friendly" meals, while the adults nosh on other more nutritional things. On Christmas my SIL fed the toddler a kiddie cup serving of mac and cheese, rather than the offerings laid out for everyone else. Sure some of it wasn't appropriate for a wee one but other things were fine like turkey, peas, steamed carrots et cetera. Others I know feed their kids a steady diet of mac & cheese, hot dogs, frozen pizza, anything in a "snack cup," spagetti-o's, and other such crud. Severe lack of veggies and fruits.
My mom keeps telling me that just because it isn't my way or her way or MIL's way it's still okay, I can't bring myself to agree. There's something to be said for having been raised by Hippie, back to nature, nutritionally concious parents. Part of it was the laid back approach to food, part was not having the money to spend on special "kid food" and a big part was a concentration on all the homegrown and home canned fruits and veggies from our garden, plethora of berry patches and pseudo-orchard. I learned to like good food rather than prepackaged crap.
I've been an you have what everyone else is having type mom, within reason. There are a few things that the adults love that my 11 y-o won't touch, she's tried them and just plain doesn't like them, no big deal. She won't touch risotto or Thai curries, but has made several tries with them without any pushing from me. She also prides herself in the "weird" foods that she loves, and takes great pleasure in disgusting her friends with some of her favorites. Always makes me giggle when I overhear the "eews" buttociated with her talking about the stuff she likes, since she started eating seafood at about 2 1-2 she has yet to meet a fish or shellfish she didn't like, right down to uni. Veggies favs are brussel sprouts and artichokes, celeric and parsnips rate high as well. Venison, Elk, Antelope, & Bison trump beef.
Report card reward is taking her out to dinner at the restaurant of her choice for making honor roll. Within the Portland, ME area we always end up at either a little ethnic restaurant, BenKay, Fuji, Street & Company, Dimillo's, or oh my poor wallet Fore Street.
Kid's eat what they are used to it's wholey up to the parents to determine if their children prefer healthy foods to calorie ladden garbage lacking in nutritional value.