Yeah that is also common.
There is a bit of an issue when it comes to how a method looks on paper to a highly educated, smart and high ranking scientist and how it works out in real life when you have McDonald's wages staff responsible for administering the test. Add into that machines designed by different companies to different standards, especially PCR machines that break every goddamn 5 seconds and businesses that expect their min wage staff to run everything without a hitch and only allow them time to run the test without issues, and you can see where the problems creep in.