A mixture of apathy and laziness.
Truly, that is what it is. no one REALLY cares about those vague people they don't know in a country they'll never visit. And why should they? What inconveniences their daily lives to make them do this?
We throw away so much food in the US alone that we could offer an entire country 4-star meals for free. No one is consuming the food, no one is hurt by it being used vs trashed, this is just pure trash food we're talking. We could definitely start freeze-drying close-to-expiration-date food that grocery stores are trashing and making and providing at least simple, cheap mass-distribute-able meals like soups, stews, breads, etc. that would at least provide some with one meal a day. That would prevent complete starvation, and give the proteins, carbs, and fats that children and adults both require to survive and sustain themselves. Many people in the world live off total garbage--Haitians eat mud pies for meals. I mean, real mud pies. That's all it is. Over-priced dirt.
I can run a family of four off of $50 a month, and we're being luxurious with that. I know for a fact we can feed the world without it inconveniencing any of us.
1. Make it mandatory for grocery stores to donate all food the day of its expiration date vs throwing it away to food-prep centers.
2. Create day-to-day government-paid jobs (as in, you show up that day, and work, and if you want to work again, you show up again) and put prisoners to work taking food donations and prepping them for drying, freeze-drying, or freezing.
3. The equipment needed to do all of this isn't THAT expensive to buy and operate. Plates and cups, bowls and forks, and spoons are tossed by the thousands here in the US. We can, instead, get some of those goodwill plates and bowls and send them over to countries for people without them.
4. Church missionaries and volunteer organizations already in place can take food out to the countries in need that aren't the BEST, but that offer the bare minimum in necessary calories and nutrients for adults and children. A piece of bread, some full-fat milk for children, some fresh water, and a bowl of hearty stew is a lot more than many get every day.
Boom. Done. But organizing all of that sounds like a whole lot of work.