Just speculation:

The houses got expensive because homeowners wanted housing to be an investment, so they voted for laws that make it harder to build or densify housing.

Cars are expensive because the government puts tariffs on perfectly good imports to protect the American car companies. The American car companies produce garbage, and even the electric car companies like Tesla and Rivian are producing super-high-tech luxury land yachts. The government incentives are also captured to produce huge trucks, and many states don't have regular inspections, so lifted trucks are common. The companies don't want to build and sell small cars because the perception is that a small car is going to get pancaked in a crash with a bigger, heavier car. Gas prices don't matter because the government artificially suppresses them, sometimes with war.

Corn and dairy are cheap because the government subsidizes them at the behest of the corn and dairy lobbies, which use small good ol' boy farmers who don't even exist as their marketing. A lot of the corn goes to ethanol for fuel, even though it's a crappy fuel and an acre of solar panels results in many more miles of EV driving than the same acre of corn ethanol. So you can also get a cheap soda and a cheap cheese pizza, but a lot of the food pipeline is captured by seed monopolies and middle-men. Somehow milk became a bit of a right-wing meme, and it's basically a naturally-occurring dessert, so people love milk even though it's not good for you and not a good way to get nutrients.

> Even food where normally you could walk in a shop

You aren't supposed to walk in America. You're supposed to drive. Don't get me started lol