At every point in the supply chain (grow, pick, sort, package, deliver...) a % of produce becomes more expensive to keep than to throw. So it being dropped.

I'd think that most such waste are still used efficiently. They may not be fit for the stresses of being shipped and stored the full distance to the supermarket and in your home, but much can still be used for animal feed and compost.

Right. Also, there are plenty of other uses of vegetable (by which I mean all non-animal, not just veggies) waste matter too, uses of all kinds, including industrial, home, medical, etc. Just randomly check out say Wikipedia articles for 10-20 common vegetable matter sources, such as corn, coconuts, bananas, soy(a)beans, guar, etc., to get a better idea about this.

Is that not overproduction in a sense?

Food shortages are really really bad even for small amount of time which is why food is over produced in excess.

Not exactly. For example, if you have a picker machine harvesting 80% of crop, and manual work ain't cheap (it's Norway), you'd probably throw 20%. But you can't "ungrow" it in any meaningful sense. Agriculture is complex.

One "solution":

Invite people to come down to hand-harvest the rest of it. Charge them a nominal fee (if at all).

Yes that is what we do here. It’s inspiring but the impact on food waste is negligible.

This sounds more wasteful to me. In terms of manpower and cost of commute.

If it's cheaper for that person to commute in order to eat then it's probably less wasteful from a financial perspective at least. Definitely possible to be even less wasteful of course, but I think without perfect weather and population models (which will never truly exist) it'll be hard to eliminate waste to a certain extent.

Something like this is usually not done out of economic incentives, but because of ethical and emotional incentives. In the end people do it to feel good, but might do more harm, just in another way.

This is true. Often times it is tilled back into the ground. Food Banks get this produce for free(less the cost of packing and shipping)

Shouldn’t that be exported to underfed populations?

At what energy cost?

Donating your overproduced (and likely subsidized) food to poorer countries also disincentivizes food production there, thereby perpetuating the food shortage problem.