In the US, we have made a conscious decision many years ago (before Obamacare and carried through Obamacare) that such tests are to be carried out at a providers office. The reason for that was so that the tests are a) done correctly, b) not done during the window phase so that people are not falsely reassured, and c) because people can be selfish idiots and they would test themselves everyday burning up Medicare, Medicaid, and private insurance dollars inappropriately.
In some other countries, they make such tests over the counter.
There have always been tests available in the US. But you have to go to your doctor.
When the CDC guy was grilled about this by a Dem in Congress last week, he explained this. Of course, the media spin that into another “the US healthcare system sucks” and another “Trump sucks” storyline when in fact, it was just another example of fake news being pedaled to the underinformed and misinformed.