Literally in the linked Wikipedia article:

"Although cast-iron cookware is known to transmit iron to food during cooking, the cost to obtain it is prohibitive for most of the individuals living in poverty in rural Cambodia, who earn less than $1 per day."

In what world would a cast iron pan be cheaper than a small ingot?

It seems like it would be simpler and easier to just give them skillets than faffing around with ingots. If one is worried about the perception of value or suspicion of gifts one could offer to trade them for their existing cookware.

Of course it would be simpler and easier but who is going to pay for it?

Cambodia is a nation of around 15 million people and a large proportion of them are affected by iron deficiency. You are talking about trying to get skillets/ingots into the hands of hundreds of thousands of people, if not millions.

Even cutting the cost of each item by $1 reduces the overall cost to either the organization(s) running the program or the poor people of Cambodia by hundreds of thousands of dollars. The organizations running this program and the poor of Cambodia aren't sitting on an infinite pot of money.

The economic upsides from improved public health outcomes make it seem like a textbook case for foreign aid - it's easy enough to quantify the cost of the iron deficiency. Admittedly I'm thinking in autocratic terms rather than about the need for buy-in and all the other factors.

Sure, but the iron fish option is cheaper and just as effective. With the money they're saving but using ingots instead of whole skillets, they can solve other problems too.

The weight also plays a big role, especially since they're carried around a lot.

That's a point I didn't consider.

What world? I don't know. I searched and find this website before commenting: http://www.luckyironfish.com/shop , which says It costs $25 each, while you can find $22 iron pan on Amazon.

Sure it might be cheaper in Cambodia, then the price of iron pans would be lower as well.

They didn't just use an ingot, they shaped the ingot into a lucky fish, which also costs money.

It's $25 because it's buy one - give one free. http://www.luckyironfish.com/facts (At the bottom).

Buying new pans is such a stupidly colossal waste of money for low income families. They already have pots and pans, and definitely don't need more. An ingot is something they can easily accommodate. And it probably costs a whole lot lesser than 20 USD.

Who wants to put an ingot in their food? But a lucky fish? We could all use some luck.

And the good thing about a fish rather than a pan is you can put it in your soup pan, your wok, your fry-pan, etc. Try putting your cast-iron pan into your wok!

The ingots were distributed for free, and likely cost under a dollar each to manufacture in bulk.

It's $25 for you, because online sales are supposed to pay for free distribution.