It seems like you've done the research here: how do you know how you are supposed(?) to do the test in the US?
Here in my municipality in Norway the media keeps repeating how/where/when to get tested, and if anything important changes the municipality will literally send a SMS to all its citizens to ensure as many as possible are up to date.
From my admittedly limited experience with the US (NYC/tri-state area) I get the impression that information is often hard to find and hard to understand. This could of course be caused by cultural or lingual differences since I'm neither American nor a native English speaker.