Not to mention there are some serious supply chain issues with getting the stuff you need to do this sort of testing. It's not like the US is the ONLY country that wants to get it's hands on these supplies. It's going to take quite a bit of time before we get beyond testing health care workers and first responders for antibodies.
In Minnesota, the U and the Mayo clinic created their OWN antibody testing which DOES NOT depend on chemicals or equipment with known supply chain issues. I thought that was particularly smart. Even so, they are talking about testing capabilities of 10-15 K per day for each. Since we have roughly 6 million people, that still is a long *** time (200 days or so) just to get through every person in this state one time...and of course, subsequent testing for antibodies is going to be required if you test negative the first time, etc. None of this is quick. But, at least we've got something and are getting started.