Americans throw out more food than plastic, paper, metal, and glass

Even if you ignore the symbolism of throwing food while people still die of hunger, I am surprised by the "so what?" reaction of this crowd. Isn't YC about improving efficiencies? Yes there is waste elsewhere, the average server utilization in a data center is 12% but that's one reason the cloud came along with a 60% utilization (see http://www.boozallen.com/media/file/Economics-of-Cloud-Compu...) and new technologies like Docker will likely make that even higher.

So instead of saying "So what?" shouldn't we say: "we can do better and this is a business opportunity"?

Basically, yes. In developed countries we spend a historically small percentage of our income on food, because food is cheap and abundant.

Meanwhile, as you say, the problem with starvation is a lack of purchasing power. Amartya Sen won a Nobel prize for showing this, in fact. Over and over we see regions with famines exporting food, not importing food; Sen initially showed this was the case for the Bengal Famine of 1943, but it has been seen many times. People think the Irish potato famine was all about potato blight, but to quote Wikipedia "Records show Irish lands exported food even during the worst years of the Famine" and "Ireland exported approximately thirty to fifty shiploads per day to Britain, which was more than enough to feed the population." The same pattern has shown up in Africa over, and over, and over, for example in the Somali famine of 1981, or the Somali famine of 2001.

(This is also why food aid to stricken regions so frequently makes things worth. Donate a few hundred tons of food, and the market for food in the region crashes. Good for the urban poor; terrible for the rural farmers and pastoralists who are usually the primary victims of a famine. Worse, "death spirals" have been documented where the price of cows drops so low that farmers can no longer afford to feed them, and end up having to slaughter them all, just as the market price is at the lowest. Then when food prices recover, the herds are dead and the farmers are bankrupt, and can afford neither food nor new cows. And the famine keeps on rolling.)

In short: You're right. Food wastage in America has no impact overseas.

Edit: There's also some political issues. India is currently fighting tooth and nail to protect the millions of small grocers and shopkeepers from the international supermarkets and "big box" retailers. India points out—correctly—that if WalMart or its kin come in, many of those small shopkeepers will lose their jobs. Economists point out—correctly—that the existing system is horrifically inefficient. For the system as a whole, those jobs are a massive cost centre, begging to be rationalised with automated warehouses, containerization, RFID tags, the whole 9 yards, instead of the archaic, expensive, inefficient system now that wastes so much of what passes through it through wastage, overheads, spoilage, etc. The same fight is also brewing over farming; peasant farmers are horrifically expensive and inefficient, but while a few mega farms could produce several times as much food for less total cost, they would do so with a tiny fraction of the manpower. And the urban jobs for the peasant farmers do not exist, and throwing them out of work would be a humanitarian disaster which the Indian government is not equipped to deal with. And so on. Food is cheap and abundant in the West as part of a massive system of technology and infrastructure; as much as we might wish otherwise, it cannot be easily grafted onto a non-Western society without major changes which Africa and India, at least, are not yet able to embrace.

If Australia didn't have the economic capacity to import there may have been a shortage to the extent that some poeple would have starved, but what would that really look like? Expensive food. Rich people wouldn't starve.

There's not much business opportunity in people who don't have money.

Assuming you turn the compost regularly, it's an aerobic process. However, if you build the heap too high, and/or it gets too wet, and/or you don't turn it often enough, it can go anaerobic. I believe that's unlikely to happen on a homeowner scale, and presumably at municipal scale they'll have industrial infrastructure to turn it regularly until it has finished decomposing.