Is it possible that the manufacturers simply want to pay as little as possible to get these things manufactured, and that they can pay people elsewhere (like in China) far less that they can pay US workers? I am no expert, but this site claims that rent prices in the US are, on average, 150% higher than in China and the cost of groceries are 72% higher.
It seems to me that Apple can get the same work done in China and pay the worker far less than they would have to pay a US worker (in terms of equivalent spending power).
The cost of living in China has been rising steadily for the last few decades as the country has gone from a backwater to a manufacturing powerhouse. Chinese labor rates actually aren't that much less than US ones any more, and so some manufacturing is going to even cheaper places now (e.g. southeast Asia, Africa).
As for milk and cheese, it's the same in Japan: those aren't big parts of the local diet, so the supply is very small and the prices high. Cheese is probably the biggest complaint about food I've heard about in regards to Japan from westerners in all the things I've read or watched on YT: the food in Japan is generally considered wonderful, except cheese: it's hard to find much variety, really tiny, and very expensive. The US isn't that different, if you're looking for some food that's common on the other side of the planet and not well-known here: try finding a durian or starfruit in your local grocery store. You'll probably have to go to an Asian grocery store to get it, unless you have a fancier store near you and a large Asian population.
https://www.numbeo.com/cost-of-living/compare_countries_resu...
It seems to me that Apple can get the same work done in China and pay the worker far less than they would have to pay a US worker (in terms of equivalent spending power).