>> "Test everyone!" To what end? You don't need to test people in order to know if they need an ICU. The ICUs are not full - and you don't need more testing to tell you that. The main benefit to more testing would be that people who are self-quarantining due to potential exposure could maybe stop self-quarantining earlier. That's a fairly marginal benefit.

You underestimate human stupidity :) People self-quarantaing is a sign of great awarenes of the danger. Meanwhile there are millions of people who ignore symptoms because "it's just a common flu, not coronavirus, don't be paranoid". Testing everyone would help identify and quarantaine those people (against their will, if necessary).