This is an interesting article:
http://www.slate.com/articles/life/...ibition_and_emmett_holt_gave_rise_to_kid.html
I don't think it is all about picky eaters. I also think it is about cost.
And as far as the comment about how kids in the 20s or 60s were better...eating what is put in front of you as an American middle class child in the 1960s does not equal an adventurous eater. My father-in-law was born in the 1940s to a poor rural family and you better believe he ate everything his mom put in front of him. When he went in the USMC, he also ate what he could. You could actually argue that he is less fussy than some people on dining threads who won't eat pizza outside of NY or won't eat at an Olive Garden or McDs because it's not good enough for them. However, he is one of the least adventurous eaters I know. He found something to eat at Boma, for instance, but was not a big fan.
Also, the parenting thing, as others have said, I have 3 children and they are all different. Even my twins who have been exposed to the EXACT same food have different tastes. My son is much more picky than my daughter. We went to a party that had chicken from a Caribbean restaurant and rice and beans but also pizza and chips. My daughter ate the Caribbean food, my son wouldn't even eat the pizza because he has decided he doesn't like sauce on pizza because it is too spicy.
I know that Americans have a generally unhealthy diet, but I'm not sure that means that kids from other countries have no "fussy" eating. My kids might turn their noses up at curry, but an Indian kid might not want to eat sushi. My kids wouldn't eat escargot, but they eat venison regularly.