Yeah - that's great if it's an option. But what about someplace like Head Start where the child is attending that specific daycare because they are from a low-income family and the parents may not have the option of packing lunches and snacks or moving their child to another daycare.
Nutrition and/or adequate caloric intake is very important in the development of good physical health and intellectual functioning at this age.
Half a sandwich for a child under the age of six is not sufficient for lunch. And if a kid says he's still hungry- he's probably still hungry- which means he hasn't had a snack before lunch.
Unless the child is clinically obsese and obviously has a problem with the hunger 'off switch' which tells someone when they've had enough to eat - I'd listen to him if he said he was still hungry.
It's sort of sad to think that anyone thinks an answer to this is to just switch daycares or pack more food from home, as if this is an option for every parent or child. There are a lot of kids for whom this isn't an option and they might be sitting there hungry- with no one trying to find a solution for them.