It hurts to watch you child starve because they are being picky. I had a teacher tell me she didn't want to eat peas one night, so her father sent her to bed hungry. She woke up a few hours later, went downstairs to her cold plate of peas still on the table, and ate the whole thing.

I had a classmate in high school who ONLY ate pancakes and fries. He was from a wealthy family and his mother had various supplements she would put in the pancakes to keep him healthy. We went on a week long canoe trip where you obviously can't eat pancakes and fries 24/7. 3 days in, this guy is starving, and for the first time in his life had pasta, trailmix, and eggs.

Children don't have fully developed faculties for reasoning, you can't take a reasonable approach to solving pickiness. Things seem to taste better the hungrier you get, so I think the approach to pickiness is to starve them out.