400-600 per day? That would be 40-60 per hour in a 10 hour shift. No way that is possible while maintaining proper hygiene.
I went to the original article in the Chicago City Wire and it's worse. They are running two 3 hour shifts. It's certainly the entire test site doing 400 to 600 per day, and not just one technician.
Also, she doesn't say how she knows “A lot of people have high antibodies." The article doesn't mention if they tested for antibodies. As a phlebotomist, she draws blood. It does not say that the drive through is drawing blood. I doubt they are. She is likely referring to blood she draws during normal duty. How she knows the results is also unknown.
The newer self swab test pretty much just means handing out the kits and collecting them again and then running the assays.
Why not if you have 10 people doing the tests? That would be 4-6/person/hr.