I blame lazy parents. The message is meant to be “You shouldn’t be picky, you should be thankful that you’re fortunate enough to have access to such quality food. There are people in much worse conditions than you, which much worse food security, who would gladly eat this broccoli/peas/whatever.”
But most parents just say “there are starving children in Africa” and leave it at that.
Well selling things in the west is more profitable. Our demand and food waste means that supply could have gone somewhere else. If a distributor knew our market was full they should gear to sell somewhere else. Either way its a macro argument that doesn't mean much.
The message isn't "eat this to help starving kids" the message is "you could be a starving kid so get over yourself and eat the food you have abundance of"