Because, strangely, it influences our design
Companies in the U.S.A. make a lot of useful and high-performance components, which are usually of high quality and well documented. Some components, such as CPLDs, FPGAs, very high-performance analog parts and ADCs, seem to be available only from U.S. sources. Unfortunately the U.S. government has draconian and complex regulations regarding the export, and re-export, of these parts. It is currently engaged in strengthening these regulations, so we are not even on a stable footing. If we use regulated parts, and re-export them from Canada in defiance of regulations, our supplies (at least) will be cut off.
If nobody outside Canada and the U.S.A. expresses interest in a project, we can use these parts freely. Otherwise we need to limit or eliminate our use of parts made or sourced in the U.S. Suppliers in the U.S. please take note.
As far as I know, no country other than the U.S. makes magical parts, then tries to put the djinn back in the bottle.
China, Taiwan, and Korea make cheap, high-performance and interesting parts, particularly in microprocessors and memories. Commonly, they regard their datasheets as top-secret documents, and they often do not produce an English translation. This makes designing with such parts a royal pain, and in some cases impossible. If we have to sign a non-disclosure agreement to get data, as some manufacturers require, we cannot make a truly open-source project. Quality control is not always to western standards. Substituting such parts for U.S.-made ones will increase development costs, but decrease unit costs, so it is really appropriate only for large-volume projects. U.S. export regulations may distort this tradeoff.
European and Japanese manufacturers make good, well-documented parts which have excellent performance, but not all types of part. They generally lag in microprocessors and related parts. Where we can get adequate performance using these parts they are always preferred.
If you know of any exceptions to these generalisations, please tell us on the Forum.