Our entire consumer economy is built around chasing costs as low as possible, which is why many forms of manufacturing have been either automated or off-shored to countries where it's cheaper. There are raw materials we simply can't obtain domestically, or not cheaply, and so there is literally no infrastructure to do so. Not to mention there are foods which simply can't be grown here. All of which has to be imported, and once you start throwing up trade barriers, everything gets more expensive.